IEEE TRANSACTIONS ON ELECTRONICS PACKAGING MANUFACTURING, VOL. 30, NO. 2, APRIL 2007
115
Surface Resistivity Characterization of New
Printed Circuit Board Materials for Use
in Spacecraft Electronics
Andrea Bulletti, Lorenzo Capineri, Senior Member, IEEE, Maurizio Materassi, and Barrie D. Dunn
Abstract—New dielectric materials have been introduced for
printed circuit board applications, such as Thermount and polyimide with the aim to match the requirements for high speed and
high density of electronic devices that are planned for new spacecraft electronic boards. Before these newer substrate can fully
replace the well-known space-approved material epoxy FR-4, it is
necessary to investigate more deeply their electrical and mechanical properties. The scope of this study is to report quantitative
characterization of the surface resistivity for the different material
samples under various testing conditions that include relative
humidity, temperature, solder flux contamination, and corona
discharge. The surface resistivity results are reported for sets of
samples measured under a combination of testing conditions.
Index Terms—Corona discharge, electrical insulation testing,
flux contamination, printed circuit boards (PCBs), surface resistivity.
I. INTRODUCTION
HE DESIGN of electronic printed circuit boards (PCBs),
with high-density/high-speed components, requires the
design and fabrication of multilayered printed circuits on dielectric substrates with high-quality materials. Over the years,
electronic components manufacturers have decreased package
pin pitch from 1.27 mm less than 0.5 mm. It is also necessary
to find materials for PCBs with a high glass temperature ( )
and low thermal expansion coefficient (CTE) in order to use
high-temperature soldering processes and multilayered PCBs.
Meanwhile the operating frequency of digital and telecommunications electronic components are rapidly reaching the
1-GHz frequency. This trend will also be followed by space
technology, and there is a need to develop electronic packaging
applications which are lighter, faster, and smaller. There are
now commercially available high-quality materials like Thermount and polyimide that are good candidates to replace the
well-known glass epoxy composite laminate, FR-4, that has
been the workhorse for European PCB assemblers. Thermount
T
Manuscript received December 14, 2005; revised September 28, 2006.
A. Bulletti and L. Capineri are with the Department of Electronics and
Telecommunications, University of Florence, 50139 Florence, Italy (e-mail:
andrea.bulletti@unifi.it).
M. Materassi is with the Alcatel Alenia Space Italia, 50013 Campi Bisenzio
(Florence), Italy.
B. D. Dunn is with the Materials and Processes Division, ESA-Estec, 2200AG
Noordwijk, The Netherlands.
Color versions of one or more of the figures in this paper are available online
at http://ieeexplore.ieee.org.
Digital Object Identifier 10.1109/TEPM.2007.899075
is a laminate of epoxy and nonwoven aramid (100%) reinforcement manufactured by Dupont. Thermount offers several
performance benefits over standard materials: low in-plane CTE
(240 C);
(7–9 ppm C) depending on resin content; high
low dielectric constant (4.0); provides excellent dimensional
stability ( 0.03 ); improves fine feature formation due to
its smooth surface; and enables high-speed laser microvia
formation [1]. However, Thermount absorbs more moisture
in respect to standard glass epoxy materials when exposed
to high-humidity and high-temperature conditions [2], and
moisture level in a dielectric substrate could significantly affect the electrical properties. Also, polyimide material offers
several performance benefits Thermount material: low -axis
CTE (45 ppm C); high
( 250 C), but it absorbs more
moisture with respect to standard glass epoxy materials when
exposed to high-humidity and high temperature conditions.
Electrical characteristics of these materials are often guaranteed in standard operating conditions, but the influence of the
combined action of several environmental factors is not yet fully
investigated. According to a previous work [3], the surface insulation resistance (SIR) test has been adopted in the present investigation to show the different behavior of dielectric substrates
for PCBs, and results are reported for SIR measurements carried out according to IPC-TM-650 [4]. The influence of thermal
excursion, voltage bias, and solder flux influence was also addressed as being relevant for the electromigration process that
lead to the formation of conductive anodic filaments underneath
copper pads or between vias.
The aim of this paper is to experimentally characterize the
surface resistivity ( ) of base laminates (i.e., epoxy, Thermount, and polyimide) when subjected of the following conditioning factors relevant for use of electronic boards in space
environment:
• relative humidity (RH);
• temperature;
• solder flux contaminations;
• corona discharge (CD) and outgassing phenomena in
vacuum (at 10 mbar).
Preliminary data related to surface and volume resistivity values
were searched in the technical notes and data sheets available
from the laminate manufacturers of epoxy, polyimide, and Thermount materials. These values were difficult to compare because
each referred to different test conditions of the materials: temperature, relative humidity, testing time (duration). For example,
some values were referred to test condition C-96/35/90 (that
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Fig. 1. Experimental setup for humidity and temperature conditioning tests (; = 300 mm, h = 400 mm, ; = 180 mm, h = 300 mm).
means a treatment for 96 h at 35 C and at 90% RH) or test
condition E-24/125 (that means a treatment for 24 h at 125 C)
[5].
Previous work [6], [7] report test results on the humidity/temperature conditioning of epoxy PCBs for 48 h; it was demonstrated that humidity absorption by this material caused a variation of surface resistivity and that the water absorption changed
with an increase in temperature. The effect of water (high humidity) on these various laminates is extremely important for
high-reliability circuits. In the space industry, the cleaning of
flux residues is achieved by using alcohol mixed with water, to
remove organic and ionic contaminants, respectively. Absorption of water into the laminate occurs during each soldering and
component rework or repair operation and post-baking of the
assembly does not always remove all moisture [8]. This moisture absorption (measured after baking samples when there is a
mass loss) of epoxy and polyimide materials were described in a
recent ESA study performed by the Insitut de Soudure (France)
[8].
Moreover, from the data obtained in the literature, it is difficult to compare the influence of different testing environments
because the samples preparation and measurement setup for surface resistivity are not fully described by the authors.
For our experimentation, we decided to perform measurements on 120 samples per substrate material. Such a large
number of samples have not been utilized before, and it is
expected to provide a statistically significant results.
The analysis of variation in surface resistivity after different
test procedures is reported in the conclusions and a correlation
with physical properties of tested materials is attempted.
II. TEST PROCEDURES
In general, surface resistivity of dielectric composites is
influenced by several environmental factors, so it was necessary
to establish the sequence of treatments for the batch of
samples.
Fig. 2. Vacuum unit with circular disk samples.
Fig. 3. Corona discharge unit in partial vacuum with glow in action.
Thenpreliminarytestshavebeencarriedoutinordertoevaluate
the main parameters values (duration, pressure, temperature,
humidity, voltage testing) for the various procedures.
The conditions for humidity/temperature procedure, have
been chosen on the basis of values found in the literature
[6], [7] (treatment for 21 h at 70 C at 90% RH). The
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117
Fig. 4. Experimental setup for surface resistivity measurements on circular disk samples in clean room class 100000.
conditions for flux contamination procedure and outgassing
have been chosen as reported in report ESA STM-267 [9].
Testing values used in corona discharge procedures have
been chosen according to preliminary experiments with a test
duration of 6 h at different dc voltages (300, 500, 800 V)
and pressures (1, 2, 3 mbar). Such conditions assured that
no surface breakdown was induced but only the formation
of a stable plasma in vacuum around the sample. These
preliminary tests demonstrated that surface resistivity values
of the as-received samples do not change significantly. In this
condition, the only expected effect on the surface resistivity
was a “cleaning action” by the plasma created in vacuum.
The obtained negligible variations of the surface resistivity
can be explained since the as-received samples were cleaned
and baked adequately. Therefore, a test duration of 15 min
has been adopted in our corona test procedure.
Each procedure, explained in following sections, has been repeated for the three type of materials (epoxy, Thermount, polyimide), and it is built by a combination of the following treatments:
• humidity and temperature conditioning;
• fux contamination;
• corona discharge;
• outgassing.
In order to get reproducible measurements for the surface resistivity, special care has been adopted in the samples preparation,
storage and handling, measurement protocol definition, and instrument calibration.
After each material processing, surface resistivity measurements of single samples have been carried out using a Keithley
chamber model 8009 located inside a clean room of class
100 000. Ten samples have been used for each test batch, i.e.,
ten epoxy samples, ten polyimide samples, and ten Thermount
samples.
A. Humidity and Temperature Conditioning Procedure
The conditioning procedure consisted of the following steps:
• ten samples of same type of material are tested with the
setup for humidity and temperature conditioning procedure
(see Fig. 1) for 96 h with following temperature and humidity conditions:
• temperature
70 C;
.
• relative humidity RH
This represents the accelerated testing of PCB assemblies
that might have been inadequately baked-out prior the electrical
testing in a clean room.
Fig. 5. Surface resistivity values of ten epoxy samples as received (solid line,
= 3:79 E +16 ), after flux contamination procedure (dotted line, R =
R
6:62 E +14 ) and outgassing procedure (dashed line, R =1:79 E +15 ).
B. Flux Contamination Procedure
The main flux used for the contamination was Alpha 850–33
type RA (a strongly activated flux occasionally used in PCB
reworking situations). A few additional tests were made with
a weak flux Alpha 611 E (RMA) for comparative purposes.
The contamination procedure adopted in this work consists
of the following steps:
• ten samples (same type of PCB material) immersed in the
flux for 10 min;
• draining in vertical position for 5 min;
• thermal cycling in an oven: start at room temperature, rise
to 125 C in 10 min, steady temperature for 30 min;
• samples out of oven and left cooling until room temperature is reached (10 min);
• spray cleaning with an ethylic alcohol with fixed amount of
liquid and manual removing of solid flux of residue with a
non acid-paper (clean room cloth type) soaked with ethylic
alcohol (10 min).
C. Outgassing Procedure
This procedure has been applied after humidity and temperature conditioning procedure or flux contamination procedure to
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Fig. 7. Surface resistivity values of ten Thermount samples as received (solid
= 3:03 E +16 ), after flux contamination procedure (dotted line,
line, R
=1:58 E +15 ) and outgassing procedure (dashed line, R =3:11 E +
R
15 ).
Here, we have attempted to reproduce the operational conditions for high voltage electronics that could be associated with
large solar panels, electronic power supplies and spacraft communication systems.
III. EXPERIMENTAL SETUP
Fig. 6. Surface resistivity values of ten polyimide samples as received (solid
= 2:07 E +17 ), after flux contamination procedure (dotted line,
line, R
=8:29 E +13 ) and outgassing procedure (dashed line, R =4:01 E +
R
13 ). The figure is split in two viewgraphs for different surface resistivity
range.
assess the outgassing of the samples. It represents the qualification or acceptance testing of PCB assemblies operating under
vacuum prior to integration on a spacecraft.
The conditioning procedure consists of the following steps:
• ten samples of same type of material are placed inside a
vacuum chamber for the outgassing assessment for 21 h at
10 mbar (see Fig. 2).
D. Corona Discharge Procedure
The procedure consists of the following steps:
• ten samples of same type of material are placed between
two electrodes, containing one sample, made of copper
disc (
130 mm) at distance
10 mm inside a
vacuum chamber (see Fig. 3);
• vacuum at 10 mbar for 30 min;
• gas Argon at a pressure of 2 mbar;
• corona discharge at 800 V between the copper discs for
15 min.
The experimental setup for surface resistivity measurements
is shown in Fig. 4.
This setup consists of the following:
• surface resistivity test fixture model Keithley 8009;
• high-voltage source measure unit model Keithley 237;
• electrometer model Keithley 617;
• personal computer equipped with a developed program in
LabVIEW.
The experimental setup for humidity and temperature conditioning procedure is shown in Fig. 1.
This setup consists of the following:
• plexiglas cylindrical camera:
mm,
mm;
mm,
mm;
• stainless steel tank:
• humidity probe: ELIWELL model EWHS280;
• electrical heater;
• pump unit: KNF model VDE0530;
• electrovalve.
The experimental setup for corona discharge procedure consists of Corona Discharge detection facility [10] and a turbo
molecular pump unit manufactured by BALZERS with a high
vacuum range up to 10 mbar. This facility has been developed according to the guidelines of the IEC 270 standard [11].
The measuring system is composed of a discharge resonance
detector coupled to a passive bandpass filter (30–200 kHz at
3 dB). The real-time discharge acquisition and processing device is based on a digitizer (15-MHz bandwidth, sampling 20
MS/s, 8 bit) and in-house software utility developed under LabVIEW to manage high-voltage source-measure unit for voltage
BULLETTI et al.: SURFACE RESISTIVITY CHARACTERIZATION OF NEW PRINTED CIRCUIT BOARD MATERIALS
119
Fig. 8. Surface resistivity values of ten epoxy samples as received (solid line,
=5:62 E +16 ), after humidity and temperature conditioning procedure
R
= 3:48 E + 16 ) and outgassing procedure (dashed line,
(dotted line, R
= 8:95 E +16 ).
R
Fig. 10. Surface resistivity values of ten Thermount samples as received (solid
=3:32 E+16 ), after humidity and temperature conditioning proceline, R
=6:64 E +16 ) and outgassing procedure (dashed line,
dure (dotted line, R
= 5:55 E +16 ).
R
Fig. 9. Surface resistivity values of ten polyimide samples as received (solid
=1:72 E+17 ), after humidity and temperature conditioning proceline, R
=9:72 E +16 ) and outgassing procedure (dashed line,
dure (dotted line, R
= 2:74 E +17 ).
R
Fig. 11. Surface resistivity values of ten epoxy samples as received (solid line,
= 7:27 E +16 ), after corona discharge procedure (dotted line, R =
7:22 E +16 ).
generation and electrometer instrument for current detection by
general purpose interface bus (GPIB) connection.
All of these substrates were procured by manufacturers that
supply these products to the European space industries.
IV. SPECIMEN PREPARATION
The specimen preparation is an important part of this work in
order to compare the effects after different type of conditioning.
The total number of samples is 120 and their nominal dimensions are: diameter 70 mm ( 0.2 mm) and thickness 1.6 mm
( 10 ). They have been divided into smaller groups for the
different tests. The materials used for this test are as follows:
• epoxy FR-4, Duraver E-Cu quality 104;
• polymide, Type N7000–1;
• Thermount 55RT, DUPONT, Reinforcement 2.0N710.
R
A. Sample Cleaning, Marking, and Baking
Samples have been cleaned one by one with pure isopropyl
alcohol according to ECSS–Q–70–08A [12] and, subsequently,
each sample has been inserted into small sterile plastic containers with identification markings.
Then all samples have been baked for 4 h at 125 C according
to ESA STM-267 [9] (see Fig. 4), and finally a dimensional
control has been made using a digital receiving gage with an
accuracy 0.01 mm. All dimensions fall within the tolerances
of the standard PCB fabrication process.
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Fig. 12. Surface resistivity values of ten polyimide samples as received (solid
=2:78 E+17 ), after corona discharge procedure (dotted line, R =
line, R
1:38 E +17 ).
Fig. 14. Surface resistivity values of ten epoxy samples as received (solid line,
= 3:60 E +16 ), after flux contamination procedure (dotted line, R =
R
5:68 E +13 ) and corona discharge procedure (dashed line, R =3:81 E +
14 ). The figure is split in two viewgraphs for different surface resistivity
range.
Fig. 13. Surface resistivity values of ten Thermount samples as received (solid
=5:37 E+16 ), after corona discharge procedure (dotted line, R =
line, R
7:22 E +16 ).
Subsequently, these samples have been stored in dry packs
with desiccants using the methods described in ESA STM-267
[9]. All operations and measurements were performed in a clean
room (class 100000).
values of epoxy, polyimide, and Thermount samples after
corona discharge procedure are shown in Figs. 11–13 for three
different groups of ten samples each.
values of epoxy, polyimide, and Thermount samples after
contamination with flux Alpha 850–33 and corona discharge
procedure are shown in Figs. 14–16 for three different groups
of ten samples each.
V. RESULTS
VI. COMPARISON OF MEASURED SURFACE RESISTIVITY
VALUES WITH DATA PROVIDED IN THE LITERATURE
The
values of epoxy, polyimide and Thermount samples
after contamination with flux Alpha 850–33 and outgassing procedure are shown in Figs. 5–7 for three different groups of ten
samples each.
values of epoxy, polyimide, and Thermount samples after
humidity and temperature contamination and outgassing procedure are shown in Figs. 8–10 for three different groups of ten
samples each.
In order to compare the measured values of the surface resistivity with other data reported in the literature, a search has been
carried out among some manufacturers of base PCB materials.
It has been found that the standard IPC-4101 [4] is generally
referred to by PCB material manufacturers in their commercial
materials specifications. This standard reports the minimum requirements for the surface resistivity measured under two operating conditions (C-96/35/90 and E-24/125). The first condi-
BULLETTI et al.: SURFACE RESISTIVITY CHARACTERIZATION OF NEW PRINTED CIRCUIT BOARD MATERIALS
121
Fig. 16. Surface resistivity values of ten Thermount samples as received (solid
= 1:88 E +16 ), after flux contamination procedure (dotted line,
line, R
= 1:08 E +15 ) and corona discharge procedure (dashed line, R =
R
2:00 E +15 ).
TABLE I
COMPARISON BETWEEN IPC 4101 [5] VALUES FOR EPOXY, POLYIMIDE,
AND THERMOUNT MATERIALS, MANUFACTURERS VALUES FOUND IN THE
LITERATURE AND THE EXPERIMENTAL VALUES FROM THE PRESENT STUDY.
THE CONDITIONING IS THE SAME STANDARD C-96/35/90 FOR ALL CASES
Fig. 15. Surface resistivity values of ten polyimide samples as received (solid
= 1:76 E +17 ), after flux contamination procedure (dotted line,
line, R
= 5:03 E +13 ) and corona discharge procedure (dashed line, R =
R
7:20 E +13 ). The figure is split in two viewgraphs for different surface resistivity range.
tion has also been adopted in our experiment, but with a higher
temperature (70 C instead of 35 C), and so the latter can be
considered a more stressful condition. The test method for measuring the surface resistivity is the IPC-TM-650, n. 2.5.17.1 [13]
and it refers to [14], which has been also adopted for our measurements.
Table I reports the IPC-4101 [4] minimum values, the mean
experimental values acquired in this study, and the values provided by three main PCB material manufacturers (Arlon, Isola,
and Nelco). Each value is referred to a specific type of FR4 or
polyimide that is reported in Table I.
VII. DISCUSSION OF RESULTS
According to previous experimental data we can analyze the
variations of the surface resistivity.
• For the samples as received from manufacturer, polyimide
material shows the highest values of surface resistivity respect to Thermount and epoxy.
• Contamination with flux Alpha 850–33 type RA caused a
decrease of surface resistivity, for all materials treated, up
to four orders of magnitudes (see Figs. 5–7 and 14–16).
• Humidity and temperature variation and corona discharge
did not modify significantly the values of surface resistivity
with respect to the values measured for samples as received
(see Figs. 8–10 and 11–13).
• All materials showed an increase of surface resistivity after
outgassing (see Figs. 5–7 and 8–10).
• Polyimide material showed the lowest values of surface
resistivity, after all test procedures, with respect to the other
materials.
We notice that the analyses of the surface resistivity of the variations is significant because the averaged values are three or four
orders of magnitude greater than the standard deviation.
VIII. CONCLUSION
The aim of this work was to study the surface resistivity variation for three types of substrate material used for the fabrica-
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tion of PCBs. Different testing conditions reflected the cleaning
and testing of PCB assembled with components for the space
industry. The main results of this work are summarized as follows.
• The surface resistivity of “as-received” polyimide PCBs is
slightly high than those for epoxy and Thermount. When
these boards are subjected to humidity, then drying, there
is almost no change in surface resistivity. Exposure to
vacuum slightly increase the resistivity of polyimide but
has little effect on the other materials.
• Only after exposure of these substrates to flux contamination, then standard cleaning, comes a large drop in surface resistivity. This indicates that the boards absorb ionic
matter from the flux, and even exposure to vacuum will not
improve the situation.
• It is important to note that standard cleaning to
ECSS–Q–70–08 [12] may be insufficient to remove
the aggressive chemicals contained in the highly active
RA-type fluxes.
• It is recommended to continue avoiding the use of RA-type
fluxes for the component-assembly of PCBs [12].
In conclusion, these results confirm the need for scrupulous
cleaning of PCB assemblies prior to their testing of use under
vacuum. Flux contaminants should always be removed, and it
is essential to bake the boards to expel moisture that will have
been absorbed by board substrates during cleaning operations.
REFERENCES
[1] M. Weinhold, “Alternatives to FR4,” in Proc. IPC Expo 1998, High
Performance, High Density Base Material Session, Geneva, Switzerland, 1998, pp. 1–18.
[2] K. Subhotosh, Comparison of the Dielectric Constant and Dissipation
Factors of Non-Woven Aramid/FR4 and Glass/FR4 Laminates. Richmond, VA: Dupont Advanced Fibers Systems, 1999.
[3] K. W. Low, A. Y. C. Wong, and H. L. Kon, “CAF effect: Challenges
for fine pitch burn-in board design,” in Proc. Burn-In & Test Socket
Workshop, Phoenix, AZ, 2003, pp. 1–16.
[4] “Test Methods Manual,” Inst. Interconnecting Packag. Electron. Circuits, Northbrook, IL, 1994, ANSI/IPC-TM-650.
[5] “Specification for Base Materials for Rigid and Multilayer Printed
Boards,” Inst. Interconnecting Packag. Electron. Circuits, Northbrook,
IL, 1997, ANSI/IPC-4101.
[6] H. Katayanagi, H. Tanaka, Y. Aoki, and S. Yamamoto, “The effects
of adsorbed water on printed circuit boards, and the process of ionic
migration,” 2002, ESPEC Tech Rep. No. 9.
[7] K. Ermeler and W. Pfeiffer, “Influence of the ambient temperature on
the impulse withstand voltage characteristics of insulation material surface under humidity conditions,” in IEEE Symp. Elect. Insulation, Apr.
7–10, 2002, pp. 367–370.
[8] I. Charrier and J-C. Goussain, “Water absorption and drying conditions of epoxy and polyimide glass printed circuit boards,” Institut de
Soudure, Villepinte, France, 2002, Tech. Rep. No. 3506.
[9] “Impact of cracking beneath solder pads in printed board laminate on
reliability of solder joints to ceramic ball grid array packages,” European Space Agency – ESTEC, 2003, ESA STM-267.
[10] M. Materassi, B. D. Dunn, and L. Capineri, “The influence of solder
fillet geometry on the occurrence of corona discharge during operation between 400 and 900 V in partial vacuum,” IEEE Trans. Electron.
Packag. Manuf., vol. 23, no. 2, pp. 104–115, Apr. 2000.
[11] “Partial discharge measurements,” 1981, IEC 270.
[12] Space product assurance “The manual soldering of high-reliability
electrical connections” 1999, ECSS-Q-70-08A, ESA-ESTEC.
[13] “Volume and surface resistivity of dielectric materials,” Inst. Interconnecting Packag. Electron. Circuits, Northbrook, IL, 1994, IPC-TM-650
Method 2.5.17.1.
[14] “Resistance or conductance of insulating materials,” 1998, ASTM
D257-93 DC.
Andrea Bulletti was born in Castiglion Fiorentino, Italy, in 1976. He received
the electronic engineering laurea degree from the University of Florence, Florence, Italy, in 2002.
Since June 2003, he has been working as a Contract Researcher in the Department of Electronics and Telecommunications, University of Florence. His
research interests concern nondestructive testing methods for composite materials and characterization of high-voltage dielectric materials.
Lorenzo Capineri (M’83–SM’07) was born in Florence, Italy, in 1962. He received the “Laurea” degree in electronic engineering in 1988, the Doctorate degree in nondestructive testing in 1993, and the Postdoctorate degree in 1994, all
from the University of Florence.
Since 1995, he has been an Associate Researcher in electronics in the Department of Electronic Engineering, University of Florence. In 2004, he was appointed Associated Professor of electronics. His current research activities are in
design of ultrasonic and pyroelectric sensors, signal and image processing (2-D
and 3-D for ultrasonic Doppler and ultrasonic tomography, ground penetrating
radar). He worked on several research projects in collaboration with national
industries (ESAOTE S.p.A., EL.EN. S.p.A., Laben/Proel S.p.A., IDS S.p.A.),
the Italian Research Council (CNR), the Italian Space Agency (ASI) and the
European Space Agency (ESA), AEA Technology, and UKAEA (England). He
is a coauthor of four Italian patents on ultrasonic and pyroelectric devices and
about 90 scientific and technical papers.
Maurizio Materassi received the Laurea degree in physics from the University
of Florence, Florence, Italy, in 1991.
He joined Proel Tecnologie S.p.A. (now incorporated into Alcatel Alenia
Space Italia), Florence, in the same year and has been employed since then in
testing activities related to space material and processes. He is currently a Program Manager for Plegpay Instrument on board the ESA facility EuTEF of the
International Space Station, for the High Power Hollow Cathode Assembly development program, and for the New Grid Systems development program. He
is also involved in the development of payloads to be flown on board the International Space Station.
Barrie D. Dunn received the M.Phil. degree in metallurgy and the Ph.D. degree in materials technology from Brunel University, London, U.K., in 1984
and 1986, respectively.
He is currently the Head of the Materials and Processes Division, European
Space Agency (ESA-Estec), Noordwijk, The Netherlands. He has supported
all ESA space projects, particularly the telecommunication satellites and the
manned Spacelab and Columbus International Space Station element. He provides expertise on spacecraft assembly processes to INTELSAT, INMARSAT,
and national space organizations and is author of the book Metallurgical Assessment of Spacecraft Parts, Materials, and Processes (Praxis, 1997).