IEC TR 62658:2013

Roadmap of optical circuit boards and their related packaging technologies

IEC/TR 62658:2013(E) covers the roadmap of optical circuit boards, and its related packaging technologies including optical circuit board connectors and optical modules on boards. Keywords: optical packaging technology road map, roadmap of optical circuit boards

General Information

• Status: Published
• Publication Date: 14-Jul-2013
• ICS: 33.180.01 - Fibre optic systems in general
• ICS: 33.180.99 - Other fibre optic equipment
• Technical Committee: TC 86 - Fibre optics
• Drafting Committee: JWG 9 - TC 86/JWG 9
• Current Stage: PPUB - Publication issued
• Start Date: 31-Oct-2013
• Completion Date: 15-Jul-2013

Overview - IEC TR 62658:2013 (Roadmap of optical circuit boards)

IEC TR 62658:2013 is a technical report from IEC TC86 (Fibre optics) that provides a roadmap of optical circuit boards and their related packaging technologies. It surveys the state of the art and planned evolution for board-level optical interconnects, including optical circuit board connectors, optical modules mounted on boards, optical backplanes and planar embedded optical waveguides. The report explains drivers for adoption (explosive network traffic growth, bandwidth-density limits of copper PCBs, and power-consumption pressures) and outlines standardization activities and performance trends for optical circuit boards.

Keywords: optical packaging technology road map, roadmap of optical circuit boards, optical circuit board connectors, planar embedded optical waveguides

Key Topics and technical focus

• Scope and motivation
  • Growth in network traffic vs. I/O improvements in servers (traffic doubling ~every 1.5 years vs. server I/O doubling ~every 2 years).
  • Energy and bandwidth limitations of copper interconnects.
• Board-level optical technologies
  • Classification and roadmap for optical circuit boards and optical backplanes.
  • Planar embedded optical waveguides for high-density routing and reduced PCB layer counts.
• Packaging and modules
  • Optical circuit board connectors and connector classifications.
  • Opto-electronic modules on boards (optical transceivers, photonic modules) and their board integration.
• Standardization aspects
  • Role of IEC TC86/JWG9 (with TC91) in coordinating board-level optical packaging standards.
  • Performance trends and a proposed standardization roadmap for interoperability, testing and adoption.
• Benefits and trade-offs
  • Advantages highlighted: higher bandwidth density, immunity to EMI, lower power for high data rates (example: a 10 Tbps optical router shows ~20% lower power vs equivalent electrical design cited by the report).

Practical applications

• Data centres and storage systems seeking higher I/O density and lower energy per bit.
• High-performance computing and routers/switches requiring high-speed backplanes.
• System and PCB designers implementing embedded optical waveguides and opto-electronic modules.
• Manufacturers of connectors, optical modules, and board-level packaging solutions.

Who should use this standard

• Standards developers and committee members (IEC/ISO liaison groups).
• Hardware architects, PCB designers and optical packaging engineers.
• Test labs, procurement teams and technology strategists planning migration from copper to optical interconnects.

Related standards (if applicable)

• IEC TR 62658 is a Technical Report prepared by IEC TC86 (Fibre optics). Users should consult IEC catalogue and IEC TC86/JWG9 documentation for normative references, existing IEC/ISO standards, and updates to the optical packaging technology road map.

Standards Content (Sample)

IEC/TR 62658 ®
Edition 1.0 2013-07
TECHNICAL
REPORT
colour
inside
Roadmap of optical circuit boards and their related packaging technologies

IEC/TR 62658:2013(E)
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester.
If you have any questions about IEC copyright or have an enquiry about obtaining additional rights to this publication,
please contact the address below or your local IEC member National Committee for further information.

IEC Central Office Tel.: [phone]
3, rue de Varembé Fax: [phone]
CH-1211 Geneva 20 [e-mail]
Switzerland www.iec.ch
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigenda or an amendment might have been published.

Useful links:
IEC publications search - www.iec.ch/searchpub Electropedia - www.electropedia.org
The advanced search enables you to find IEC publications The world's leading online dictionary of electronic and
by a variety of criteria (reference number, text, technical electrical terms containing more than 30 000 terms and
committee,…). definitions in English and French, with equivalent terms in
It also gives information on projects, replaced and additional languages. Also known as the International
withdrawn publications. Electrotechnical Vocabulary (IEV) on-line.

IEC Just Published - webstore.iec.ch/justpublished Customer Service Centre - webstore.iec.ch/csc
Stay up to date on all new IEC publications. Just Published If you wish to give us your feedback on this publication
details all new publications released. Available on-line and or need further assistance, please contact the
also once a month by email. Customer Service Centre: [e-mail].

IEC/TR 62658 ®
Edition 1.0 2013-07
TECHNICAL
REPORT
colour
inside
Roadmap of optical circuit boards and their related packaging technologies

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
R
ICS 33.180.01; 33.180.99 ISBN 978-2-8322-0915-8

– 2 – TR 62658 © IEC:2013(E)
CONTENTS
FOREWORD . 3
1 Scope . 5
2 General . 5
2.1 Background of optical packaging technology road map . 5
2.2 Advantages of optical interconnects . 7
2.3 Planar embedded optical waveguides . 9
3 Standardization of board-level optical packaging . 9
3.1 Role of IEC TC86/JWG9 (with TC91) . 9
3.2 Optical circuit boards [20] . 10
3.3 Optical backplanes [22] . 11
3.4 Optical circuit board connectors [23]. 13
3.5 Opto-electronic modules on boards . 14
3.6 Originating standards . 15
4 Standardization road map . 16
4.1 Performance trends for optical circuit boards . 16
5 Standardization road map of optical circuit boards . 17
Bibliography . 18

Figure 1 – Data transmission speed and capability trends for network traffic and
server systems [2]. 6
Figure 2 – Internet traffic and router power consumption in Japan [5] . 7
Figure 3 – Increase of power consumption in future network . 8
Figure 4 – Comparison of power consumption of 10 Tbps electrical and optical routers . 9
Figure 5 – Discussion field in IEC TC86/JWG9 (with TC91) . 10
Figure 6 – Classification of optical circuit boards . 11
Figure 7 – Four types of optical backplane applications . 13
Figure 8 – Classification of optical circuit board connectors . 14
Figure 9 – Classification of optical modules on boards . 15
Figure 10 – De facto-standards in Japan [24] . 15
Figure 11 – Performance trends for optical circuit boards. 16
Figure 12 – Standardization roadmap of optical circuit board and its related optical
packaging . 17

TR 62658 © IEC:2013(E) – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ROADMAP OF OPTICAL CIRCUIT BOARDS AND
THEIR RELATED PACKAGING TECHNOLOGIES

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
The main task of IEC technical committees is to prepare International Standards. However, a
technical committee may propose the publication of a technical report when it has collected
data of a different kind from that which is normally published as an International Standard, for
example "state of the art".
IEC 62658, which is a technical report, has been prepared by IEC technical committee 86:
Fibre optics.
The text of this technical report is based on the following documents:
Enquiry draft Report on voting
86/442/DTR 86/453/RVC
Full information on the voting for the approval of this technical report can be found in the
report on voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

– 4 – TR 62658 © IEC:2013(E)
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
TR 62658 © IEC:2013(E) – 5 –
ROADMAP OF OPTICAL CIRCUIT BOARDS AND
THEIR RELATED PACKAGING TECHNOLOGIES

1 Scope
This Technical Report covers the roadmap of optical circuit boards, and its related packaging
technologies including optical circuit board connectors and optical modules on boards.
2 General
2.1 Background of optical packaging technology road map
The volume of network traffic is dramatically increasing due to the amount of data being
captured, processed, conveyed and stored as digital information. This information is
generated from many sources, including critical business applications, email communications,
the Internet and multimedia applications which have collectively fuelled an increase in
demand for data networking and storage capacity. In addition, the proliferation of media rich
applications, such as digital music and video sharing services is fuelling a concurrent
increase in data processing in data centres [1] . The growth in network traffic attributed to
personalized content is 20 % per month, giving rise to a doubling of network traffic every
1,5 years. However, this is out of step with the input/output (I/O) performance or I/O
throughput of servers, which doubles every 2 years. Therefore, there is an increasing gap
between the performance evolution of network equipment such as servers, and the growth in
network traffic (Figure 1) [2].

________________
Figures in square brackets refer to the Bibliography.

– 6 – TR 62658 © IEC:2013(E)
IEC  1588/13
Figure 1 – Data transmission speed and capability trends
for network traffic and server systems [2]
In general, system power consumption will increase as the volume of internet traffic expands.
By 2020, power consumption in network routers in Japan will reach the gross power
generation of Japan in 2005. An energy saving by 3 to 4 orders of magnitude in network
router technology is required in 2030 to meet the stipulated targets in the Kyoto protocol [3]
(Figure 2).
In addition, the bandwidth and density requirements for interconnects within high-performance
computing systems are becoming unmanageable, due to increasing chip speeds, wider buses
and larger numbers of processors per system [4]. The increase in system bandwidth and
density required to satisfy this demand would impose unmanageable cost and performance
burdens on future data networking and storage technologies.
An alternative to the current electrical printed circuit board (PCB) interconnect technology is
required across multiple high-speed application spaces to mitigate this common trend. Optical
interconnects are expected to bridge the performance gap between network hardware and
traffic, and give rise to a reduction in hardware power consumption while increasing
bandwidth density by over two orders of magnitude.

TR 62658 © IEC:2013(E) – 7 –
IEC  1589/13
Figure 2 – Internet traffic and router power consumption in Japan [5]
2.2 Advantages of optical interconnects
Optical interconnects will be fundamental in further scaling the performance of networking,
server, router, data storage and high performance computing technologies.
The design and development of future higher capacity network hardware will be hindered by
high-frequency electronic constraints such as crosstalk, dielectric loss, skin effect, electro-
magnetic interference (EMI) and high sensitivity to impedance matching. The maximum
permissible density of electronic transmission lines is determined by the crosstalk incurred
between electronic channels. The higher the signal frequency, the greater the separation
between electronic channels required to keep crosstalk within acceptable levels. For example,
the line pitch between adjacent electronic channels required to convey a signal data rate of
10 Gbps is 3 times larger than that required to convey a signal data rate of 3 Gbps. This
makes it more difficult to design and manufacture a high-capacity printed circuit board, as the
electronic transmission line density must decrease as the signal speeds increase. The
adoption of optical interconnects will mitigate these design constraints. Optical waveguides
neither produce nor are affected by electro-magnetic interference, and are therefore not
constrained by electromagnetic compatibility regulations that impose a severe cost burden on
the design of high-speed copper printed circuit boards (PCBs) and supporting interconnect
technologies, such as connectors. The layout advantages offered by optical waveguides will
give rise to a reduction in the functional area and layer count of the PCB. The level of
reduction will strongly depend on the application, with the more I/O intensive applications
subject to the greatest potential reduction in PCB volume.
Another advantage of the adoption of embedded optical interconnects in high-capacity
networking, server, router, data storage and high performance computing technologies is a
reduction in power consumption.
As the network traffic increases, the power consumption of network hardware is expected to
increase 5 fold by 2025 and 12 fold by 2050 [6]. For data transmission at speeds greater than
10 Gbps, current electrical interconnects will need to be enhanced by active signal
conditioning devices such as pre-emphasis and equaliser circuitry to ensure that the signal
distortion or degradation due to the mitigating factors described above remains within

– 8 – TR 62658 © IEC:2013(E)
acceptable levels. In addition, the power consumption of electronic signal drivers will also
increase. As signal frequencies increase, an electronic signal driver will need to ramp up the
signal power in order to overcome the fundamental loss mechanisms on a copper
transmission line. These loss mechanisms include dielectric loss, skin effect, and the surface
roughness of the copper trace, which accentuates skin effect by increasing the effective
surface area. Dielectric loss effects can be mitigated to some extent by using specially high
frequency printed circuit board laminate materials, however at mounting cost to the system.
Long distance optical interconnects such as single mode optical fibres for multi-kilometre data
transfer also require adaptive equalisation, but for very short distances, such over a system
backplane this is certainly not required (Figure 3).

IEC  1590/13
Figure 3 – Increase of power consumption in future network
Though optical interconnects will require active devices to convert electronic signals to optical
signals and vice versa, it is expected that the power consumption due to these conversion
technologies will be less than those due to electronic signal driver and signal condi
...