ERICSSON EXPERIENCES OF LOW HALOGEN TELECOM NETWORK
INFRASTRUCTURE EQUIPMENT
Richard Trankell, Jenny Sandahl
Ericsson AB
Abstract: The majority of the in-house designed printed boards and cables for
Ericsson high volume network infrastructure equipment use low halogen material.
Ericsson has more than ten years experience of the use of low halogen materials and
our field data show no problems related to the use in telecom network infrastructure
equipment. It is currently not possible to migrate to low halogen materials in all
telecom network infrastructure equipment applications. For example, in radio power
amplifiers a so called low loss material is needed for which no low halogen version
is currently available.
1. INTRODUCTION
The use of halogenated substances has been debated
for many years, the main reason being environmental
concern but also the risk of corrosive and toxic gases
formed in case of fire. Ericsson takes a precautionary
approach to the use of halogenated substances and
has worked with low halogen issues since the early
1990’s.
2. ENVIRONMENTAL IMPACT
The main environmental risk with organic
brominated and chlorinated substances is due to their
toxicity and persistence in the environment.
The most toxic brominated and chlorinated
substances are restricted in electronics which means
that the main problems remaining occur as a result of
improper end-of-life treatment. Toxic dioxins and
furans can be formed when electronics containing
chlorine or bromine are incinerated at low
temperatures. Dioxins and furans are highly toxic
chemicals that can persist in the environment for a
long time.
3. DEFINING LOW HALOGEN
The chemical definition of a halogenated compound
is a compound containing chlorine, bromine, fluorine
or iodine. “Halogen-free” or “low halogen” are terms
used by the electronics industry. In this paper we
have chosen to use the term low halogen and refer to
the definitions in the following standards and draft
guidelines.
 IPC-4101 [1] covers printed boards. To be
classified as low halogen a printed board can
contain up to 0,09% of chlorine or bromine and
up to 0,15% of bromine and chlorine together.
 For components other than printed boards there
is a draft guideline IPC-4903 [2] that will replace
the not approved draft IPC/JEDEC JP-709. Class
A in this draft defines low halogen such that
each plastic part in the component shall contain
<1000ppm (0,1%) of bromine and < 1000ppm
(0,1%) of chlorine if the source is from flame
retardants or PVC.
 For cables the IEC 60754-2 [3] standard contains
requirements for testing corrosive gases evolved
during combustion. This indirectly defines low
halogen, including fluorine content .
4. LEGAL SITUATION
Halogenated compounds have been debated for
many years and the most toxic substances are
restricted or proposals for restriction exist in several
parts of the world. For example polybrominated
biphenyls (PBB) and polybrominated diphenyl ethers
(PBDE) are restricted in Europe through the RoHS
[4] directive. Also in Japan, US and Canada there are
restrictions on some of the most toxic organohalogens.
There is no general ban on all halogenated flame
retardants or organo-halogen substances. For
example there is no ban on the most common flame
retardant used in electronics - Tetrabromobisphenol
A, TBBPA. As part of the current RoHS recast
process there have been suggestions to ban all
brominated and chlorinated substances, but this is
not currently part of the proposal.
In EU there is a strong trend for migrating to low
halogen material in cables from a fire safety
perspective. The philosophy is to avoid poisonous
and corrosive gases in event of fire. The Construction
Products Directive (CPD) [5] will soon add fire
performance
testing
of
cables,
including
measurements of total smoke production and acidity.
Low halogen cables will probably be necessary to
fulfill those requirements.
In US there is a different philosophy and the focus is
to prevent or delay the start of a fire. This is done by
using high performance PVC’s or fluoropolymers.
Both are materials that can emit highly poisonous
and corrosive gases if a fire takes place. Standardized
UL fire test methods in the US for cables in risers
and in ventilated areas (plenums) cannot be complied
with without using halogenated materials in cables.
5. CUSTOMER REQUIREMENTS
Many companies in the consumer product market
have chosen low-halogenated materials as a
marketing and business strategy. For Ericsson
products aimed at the consumer market, e.g. Mobile
Broadband Modules, all current customers require
low-halogenated material. This type of requirements
normally tend to gradually spill over to the business
to business sector.
For cables, product safety issues have created
customer requirements for the avoidance of
halogenated materials in some regions. Even a minor
fire incident can lead to the formation of corrosive
gases which can damage surrounding equipment
negatively inflicting high costs.
Some customers require PVC or fluorinated cables
because of their low flammability.
6. PRICE SITUATION
Generally low halogen material is more expensive.
This is true for both printed boards and cables. The
difference is mainly related to the volumes produced.
For printed boards the price difference was initially
substantial but has decreased as volumes of low
halogen materials have increased. There are now
many material suppliers who offer low halogenated
materials and depending on the printed board
manufacturer’s relation with the laminate suppliers,
the volumes used and the material type
(core/prepreg, thicknesses etc.) the price is between
5-20% higher for low halogen materials.
7. ERICSSON EXPERIENCES
Materials used in Ericsson products are proactively
controlled through our list of banned and restricted
substances [6], which is used in all purchasing
agreements and in design. Combining the list with
information on the material content in our products
through material declarations, enables a systematic
management of materials in our products.
In addition to this we offer a free world-wide end of
life take-back scheme for our products.
The brominated flame retardants PBB and PBDE are
banned for use in Ericsson products, as are several
chlorinated substances such as PCBs and shortchained chlorinated paraffins. All other halogenated
flame retardants, and chlorinated polymers (e.g.
PVC), are included on Ericsson’s list of substances
under observation, meaning that they are identified as
substances that cause concern when used in Ericsson
products and manufacturing processes. Substances on
the observation list will be substituted when
alternatives that are technically, economically and
environmentally feasible are available.
In Ericsson telecom network infrastructure
equipment halogenated materials can mainly be used
in:
 Printed boards
 Cables
 Electronic components
Work with low halogen within Ericsson has focused
on in-house designed printed boards and cables.
Ericsson has more than 10 years experience of low
halogen printed boards and cables.
Pre-study and
evaluation of
printed boards
2000
Production
of low
halogen
cables from
early 1990’s
RBS with low
halogen
printed boards
2002
Mobile
phones with
low halogen
printed board
2004
PBDE phased
out
2006
Low halogen
cables
standard in
network
equipment
Fig. 1. Ericsson low halogen history
Low halogen Mobile
Broadband Modules
2008
Low halogen
first hand
choice for FR4
printed
boards
2010
7.1 Printed Boards
The migration to low halogen printed board materials
started 2002 and today low halogen material has
become the first choice for FR4 printed boards for
our high volume telecom network infrastructure
equipment. The majority of the in-house designed
printed boards in high volume network infrastructure
equipment use low halogen laminates.
Ericsson started evaluation of low halogen printed
board materials in the end of the 1990’s. A number of
suppliers of low halogen materials for printed board
applications were evaluated, covering prepreg,
laminate and materials for high density interconnect.
A prerequisite was to have a V-0 flammability grade
for the material according to IEC 60695-11-10 [7]
and UL 94 standards.
The evaluation showed that it was possible to replace
halogenated material with low halogen and that the
supplier base was sufficient to fulfill Ericsson’s
requirements. The electrical properties of low
halogen FR4 differ slightly from those of brominated
FR4, which means it is important to consider printed
board materials early in product design. Processing
of low halogen printed board materials was
performed with minor deviations from standard
process parameters. For many low halogen
alternatives, yields in printed board production was
improved. Another positive effect was a more
uniform specification of low halogen materials,
which resulted in more robust design. For example,
more stable thermal expansion made it better suited
to the raised temperatures in lead-free soldering
processes. In addition the better dimension stability is
an important advantage as copper patterns are
becoming denser.
The migration from brominated FR4 boards to low
halogen FR4 has caused no major issues. The biggest
challenge initially was poor availability and long
lead-times for low halogen materials. This is typical
for the introduction of new materials.
For applications with low electrical signal loss
requirements, e.g. power amplifiers in radio units, a
specific “low loss” material is used. The trend for
digital units in telecom network applications is
moving towards higher signal speeds. The
performance of FR4 boards has so far been adequate
but future use of low loss materials is also being
investigated for these applications. There are,
however, currently no low halogen alternatives
available for low loss material.
Work is ongoing amongst laminate suppliers to
develop low halogen low loss materials, but these
will probably not be commercially available until
2012-2015.
When Ericsson started the migration to low halogen
FR4 boards in the end of the 1990s, it involved
higher costs and single source. Today a similar
scenario can be expected when migrating to low
halogen low loss materials.
7.2 Cables
For internal cabling in Ericsson telecom network
infrastructure equipment cabinets, low halogen
cables are used as standard. Indoor on telecom sites,
low halogen cables (e.g. power cables) are used as
standard. However halogenated alternatives, such as
PVC are offered to certain markets were required.
The migration to low halogen cables started at the
beginning of the 1990s. The main reason was
because of customer requirements for the avoidance
of corrosive gases in event of fire.
Problems associated with the stiffness of low halogen
cables can be managed if considered early in product
design.
Differing philosophies regarding fire safety result in
the need to supply halogenated cables in certain
markets.
7.3 Components
In telecommunication infrastructure network
equipment, the majority of electronic components
with an epoxy encapsulation, currently contain
brominated flame retardants.
The consumer product market is driving the
migration towards low halogen electronic
components. This will also gradually affect the
components used in telecom network infrastructure
equipment.
Ericsson follows the general development in the
component market, except for Mobile Broadband
Modules where we actively have migrated to low
halogen components (see 8.3).
8. PRODUCT EXAMPLES
8.1 Radio base station
All Ericsson designed FR4 printed boards are low
halogen.
All Ericsson designed cables used internally in
cabinets and external power cables for indoor use on
site use low halogen materials. Halogenated (PVC)
alternatives are used for markets that have such a
requirement. The status for components on printed
boards are in line with section 7.3 above.
8.2 Power Modules
The use of halogenated substances was reduced
through a design change in 2008 when the
brominated epoxy encapsulation of the modules was
phased out and replaced by an open frame design.
Low halogen printed boards for on-board DC/DC
converters and point-of-load regulators was
evaluated and tested in the beginning of 2000 with
good results.
Low halogen printed boards are currently used for
product series with low current and power levels. For
product series with higher current and power levels
special printed boards with very thick copper layers
must be used due to electrical and thermal
requirements. For those applications it has not been
possible to ensure a continuous supply of low
halogen printed boards.
8.3 Mobile Broadband Modules
Ericsson Mobile Broadband Modules for notebooks
and other connected devices use low halogen
materials in both printed boards and components.
The use of low halogen material is a requirement
from all current customers.
9. RELIABILITY ISSUES
Ericsson has more than 10 years experience of low
halogen printed boards and cables in telecom
network infrastructure equipment. No problems
related to the use in telecom network infrastructure
equipment have been identified.
For printed boards no difference in reliability has
been identified between low halogen F R 4 and
brominated FR4.
10. CONCLUSIONS
 Ericsson has more than 10 years experience
of low halogen printed boards and cables in
telecom network infrastructure equipment
 Field data show no problems regarding use
of low halogen FR4 printed boards and
cables in telecom network infrastructure
equipment
 The majority of the in-house designed
printed boards and cables for Ericsson high
volume network infrastructure equipment
use low halogen materials
 It is currently not possible to migrate to low
halogen materials in all areas of telecom
network infrastructure equipment, e.g. low
loss printed boards
11. ACKNOWLEDGMENT
The authors would like to thank all internal experts
in design, sourcing and component technology that
have provided information, for their contributions.
12. REFERENCES
[1] Specification for Base Materials for Rigid and
Multilayer Printed Boards, IPC-4101
[2] A guideline for Defining “Low Halogen”
Electronic Products, IPC-4903, Working Draft,
August 2010
[3] Test on gases evolved during combustion of
electric cables, IEC 60754-2
[4] EU Directive 2002/95/EC of the European
parliament and of the council of 27 January 2003
on the restriction of the use of certain hazardous
substances in electrical and electronic equipment
[5] Construction Product Directive, 89/106/EEC
[6] The Ericsson lists of banned and restricted
substances, 2/00021-FAU 104 04, rev B
[7] Fire hazard testing - Part 11-10: Test flames - 50
W horizontal and vertical flame test methods,
IEC 60695-11-10