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Measuring Conductivity of Proton Conductive Membrane in the direction of thickness, partⅡ:
using the 4-probe method in the direction of thickness
Report
Measuring Conductivity of Proton Conductive Membrane in the direction of
thickness, part Ⅱ: using the 4-probe method in the direction of thickness
Shuhua Ma, Hirokazu Tanaka Technical Development Headquarters
P
roton conductive membrane has been reported to exhibit anisotropic
properties in its in-plane and thickness directions in such areas as crystalline
structure, dimensional stability, and proton conductivity. 1),2) Generally, the
conductivity of proton conductive membrane is measured only in the in-plane
direction due to the availability of well-developed methods. However, these
measurements do not provide a complete and accurate grasp of the conduction
properties of a membrane. As a result, methods of measuring ion conductivity in the
direction of thickness are urgently required, especially with the successful use during
recent decades of proton exchange membranes in polymer electrolyte membrane fuel
cells (PEFCs). Unfortunately, an accurate and reliable method has yet to be
established for measuring ion conductivity in the direction of thickness of the
membrane.
Usually, higher accuracy is attained using the 2-probe and 4-probe methods to
measure conductivity in the in-plane direction. At Espec, we have investigated the
possibility of applying these methods for measuring conductivity in the direction of
membrane thickness. Preceding reports 2),3),4) have discussed the effects of interface
complexity and contact quality between test membrane and electrodes, and have
verified the feasibility of employing the 2-probe method for measuring ion
conductivity in the direction of thickness. On the other hand, the 4-probe method can
yield much more accurate measurements than the 2-probe method because it uses
reference electrodes to sample electrical potentials on both sides of test membranes.
This report will present results obtained using the 4-probe method in the direction of
thickness for measuring the conductivity of ion exchange membranes.
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Espec Technology Report No.23

Measuring Conductivity of Proton Conductive Membrane in the direction of thickness, partⅡ:
using the 4-probe method in the direction of thickness
1
Introduction
Compared to measuring in the in-plane direction, the 4-probe method of measuring in the
direction of thickness features a much smaller cell constant (L/A in σ=L/(RA))because the
membrane is thinner and possesses a larger area. Consequently, the measured resistance,
typically within the range of 0.1 to 50Ω, is significantly lower than that in the in-plane direction
when using the 4-probe method, in which resistance can be as high as 10 to 10 4 Ω according to
the temperature and humidity environments used. When measuring in the direction of thickness
with the 4-probe method, some new problems may hinder widespread practical application.
(1) Dispersion in measurement values may be incurred by unevenness of interlayers in
membrane laminates and/or contact between the reference electrode and its adjacent
membranes. Such dispersion may also be induced by the MEA (membrane/electrode
assembly) from the much thicker wire diameter of the reference electrodes.
(2) A much larger contact area between the reference electrode (which samples electric potential
on one face of the test membrane) and the test membrane, which may come from the
exfoliation and/or the crumbling of the coating layer on the reference electrode, will
(a) produce rather larger interface resistance than bulk test membrane and smaller interface
capacitance between the test membrane and the reference electrodes. With these
influences, some labile arc-like loops and/or semi-circles may arise in the Cole-Cole plot,
which will make it impossible for the 4-probe method to avoid being influenced by effects
related to interfaces.
(b) cause the hemi-circles on the Cole-Cole plot to be unsteady due to changes in the contact
area between the reference electrodes and membrane, and to be susceptible to the
fluctuations of the temperature and the humidity in the operating environment.
Furthermore, this mutability makes it impossible to measure bulk resistance of the
membrane by intercepting on a real axis such as is done in 2-probe method.
(3) When MEA specimens are produced at higher temperatures and pressures using
hot-pressing, reference electrodes frequently break off from the wires sandwiched between
test membranes and current lead-in membranes, causing functional failure. This is caused by
the creep property of the polymeric membranes that are liable to stretch and deform.
- 2 -
Espec Technology Report No.23

Measuring Conductivity of Proton Conductive Membrane in the direction of thickness, partⅡ:
using the 4-probe method in the direction of thickness
Because of these problems, input/output O/L (overload) error messages of current and voltage
in the electrochemical measurement device (Potentiostat/Galvanostat) are much more likely to
occur when using the 4-probe method in the direction of thickness than in the in-plane direction.
The difficulties in manufacturing and measuring MEA specimens have greatly hindered the
application of the 4-probe method in the direction of thickness in real ion conductivity
measurements. Furthermore, a defective MEA specimen produced by improper temperature and
pressure conditions will also lead to some failures and debase the accuracy of the measurements.
For example, diffuse and scattered points with a poor convergence domain are brought about on
the Cole-Cole plot, and/or completely singular resistance measurements may be obtained.
With the aim of overcoming the above failures and identifying the optimal specimen
manufacturing conditions as well as conditions for accurately measuring proton conductivity in
the direction of thickness of Nafion ® -like membranes, we at Espec have developed the 4-probe
technique in the direction of thickness. This report will discuss some important factors affecting
the measuring performance of the MEA specimen, including the arrangement between the
electric potential sampling electrodes and the electric current lead-in membranes, materials of
the wire and its coating used as electric potential sampling electrodes, and the forming condition
of MEA specimens. In addition, this report will also present measurement results from this
4-probe technique in the direction of thickness for Nafion117 ® membranes that underwent
different temperature and pressure pretreatments.
2
Experimental method
2-1 Equipment and materials
Table 1 lists equipment and materials used in this research.
Table 1 Equipment and materials
Equipment/materials Manufacturer
Ion exchange membrane
Cu/polyester coated wire,
wire diameter: φ0.1mm
Pt/Teflon coated wire,
wire diameter: φ0.076mm
E. I. du Pont de Nemours and
Company
- 3 -
Model/registered
product name
Nafion117 ®
The Nilaco Corporation CU-116167
The Nilaco Corporation PT-967353
Pt wire, wire diameter:φ0.10mm The Nilaco Corporation PT-351165
Insulating varnish The Nilaco Corporation Varnish, No. 7031
Impedance gain/phase analyzer Solartron Instruments SI 1260
Electrochemical interface Solartron Instruments SI 1287
Temperature & humidity chamber Espec Corporation PL-1KPH
Espec Technology Report No.23

Measuring Conductivity of Proton Conductive Membrane in the direction of thickness, partⅡ:
using the 4-probe method in the direction of thickness
2-2 Specimen preparation
2-2-1 Preparation of reference electrodes
Three types of coated wire with insulating layer were used as reference electrodes (also known
as electric potential sampling electrodes) to examine effects of the coating and the conducting
materials on the measuring performance of the MEA specimen.
(a) Cu/polyester coated wire: ready-made product used as listed in Table 1.
(b) Pt/Teflon coated wire: ready-made product used as listed in Table 1.
(c) Pt/insulating varnish coated wire: coating film formed on Pt wire by soaking bare Pt wire in
Varnish No. 7031 solution diluted with solvent mixture of ethyl alcohol and toluene 50:50 by
volume, and followed by drying in vacuum at 100℃ for 5 hours.
2-2-2 Manufacturing MEA specimens for the 4-probe method in the direction of thickness
Using the above three types of coated wires, reference electrodes were prepared by cutting one
end obliquely to be used as the electric potential sampling electrode terminal and peeling the
other end of the wire about 1 cm to be used as the connecting terminal into other external
devices.
Two steps were involved in the manufacturing process of premium MEA specimens in this
context.
First, the reference electrode was imbedded into the current lead-in membrane by placing one
reference electrode on a 50μm-thick Teflon sheet with its bevel section exactly toward the film
surface, covering that with a current lead-in membrane and another Teflon sheet in sequence,
and then following with a hot-pressing treatment at 150℃ and 400 kgf cm -2 . Second, after
removing the Teflon sheets, the MEA specimen was fabricated by sandwiching two current
lead-in membrane units made above and one test membrane pretreated under the appointed
temperature, pressure and chemical conditions, with the bevel sections situated opposite each
other and located at equipotential positions, e.g., the center of the test membrane, and then
hot-pressing them at 150℃ and 20 kgf cm -2 . The schematic construction of the MEA specimen as
obtained above for the 4-probe method in the direction of thickness is shown in Fig.1.
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Espec Technology Report No.23

Measuring Conductivity of Proton Conductive Membrane in the direction of thickness, partⅡ:
using the 4-probe method in the direction of thickness
Fig.1 Construction of MEA specimen for the 4-probe method in the direction of
thickness
2-3 Conductivity measurement of MEA specimens
A specimen fixed to the measuring cell was placed inside a temperature and humidity chamber
under constant temperature and humidity (30℃, 30-90%rh). AC impedance measurements
were taken using a computer-controlled impedance gain/phase analyzer and electrochemical
interface measuring system, and Cole-Cole (Z’-Z’’) and Bode (log|Z|-log Frequency and
theta-log Frequency) plots were obtained. The frequency limits of the sinusoidal signals were
typically set between 5MHz and 0.01Hz, with an oscillation of 10 mV.
With test membrane bulk resistance R read out according to the center of gravity of the
concentrated points on Cole-Cole plot, conductivity was calculated using the following formula.
L
=
R ⋅ A
σ … (1)
Where σ is conductivity (S cm -1 ), R is resistance (Ω), L is test membrane thickness or interval
between two electric potential sampling electrodes (cm), and A is electrode area (cm 2 ).
Equipment connection for the impedance gain/phase analyzer (IGPA), the electrochemical
interface (EI) and the membrane/electrode assembly (MEA) was shown in Fig.2 for 4-probe
conductivity measurements in the thickness direction used in this report.
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Espec Technology Report No.23

Measuring Conductivity of Proton Conductive Membrane in the direction of thickness, partⅡ:
using the 4-probe method in the direction of thickness
Fig.2 Block configuration for ion conductivity measurement using the 4-probe
method in the direction of thickness
3
Considerations and discussion of measuring
3-1 Configuration of the 4-probe method in the direction of thickness
Using the 4-probe method in the direction of thickness, the simplest configuration is that which
measures only a single test membrane, although theoretically multiple membranes can be
measured unless the MEA stack is too thick to afford stable and sound internal contacts as well a
dimensional evenness of the test membranes. As Fig.2 shows, a typical MEA specimen
configuration consists of 4 electrodes, known as electric current lead-in electrodes and electric
potential sampling electrodes, and 3 membranes as electric current lead-in membranes and test
membrane. Considering the specimen as an active electrochemical system, the equivalent
circuit 5) and the connections into the external electrochemical device can be expressed in Fig.3.
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Espec Technology Report No.23

Measuring Conductivity of Proton Conductive Membrane in the direction of thickness, partⅡ:
using the 4-probe method in the direction of thickness
- 7 -
RmCE, RctCE, CdlCE: denote resistance and
capacitance related to the electric current
lead-in membrane and the interface between
that and the electric current lead-in electrode
on the CE side.
Rm, RctRE1, CdlRE1, RctRE2, CdlRE2: denote
resistance and capacitance related to the test
membrane, and the interfaces between that
and reference electrodes.
RmWE, RctWE, CdlWE: denote resistance and
capacitance related to the electric current
lead-in membrane and the interface between
that and the electric current lead-in electrode
on the WE side.
Where subscript CE stands for the electric current lead-in electrode or membrane on the CE side,
RE1 for the electric potential sampling electrode on the CE side, m for the test membrane, RE2
for the electric potential sampling electrode on the WE side, WE for the electric current lead-in
electrode or membrane on the WE side, respectively. Furthermore, ct and dl refer to charge
transfer and double layer as conventionally for an electrochemical interface.
Fig.3 Connections and equivalent circuit for MEA specimen using the 4-probe method
in the direction of thickness
Espec Technology Report No.23

Measuring Conductivity of Proton Conductive Membrane in the direction of thickness, partⅡ:
using the 4-probe method in the direction of thickness
Fig.3 demonstrates that the impedance pertaining to the electric current lead-in membrane and
its interfaces with electric current lead-in electrodes, RmCE, RmWE, and RctCE, RctWE, CdlCE, CdlWE, are
situated outside the electric potential sampling measurement system, and thus have little
influence on measurement results. As a result, bulk membrane resistance Rm can be measured
accurately using this method, provided the impedance related with RctRE1, RctRE2, and CdlRE1, CdlRE2 are small enough. This impedance can be reduced by adjusting hot-pressing conditions and
manufacturing processes of MEA specimens. Hence, we may infer that the electric current lead-in
electrodes, CE and WE, may be omitted by substituting two electrode terminals of the measuring
cell. Also, the electric current lead-in membranes of CE and WE do not affect the results even if
different kinds and/or thickness of membranes are used, although they should possess the same
current-conducting carriers as the test membrane, viz., either electron, proton, or other ions. In
addition, test membranes can be pretreated by hot-pressing at various pressures and
temperatures, or any chemical treatments may be applied before preparing MEA specimens.
Thus, this method allows a wide range of membrane conditions.
However, it is necessary to prevent the thickness and the evenness of test membranes from
being affected when the test membrane is combined into an MEA specimen. This means that
temperature and pressure conditions must be neither too high nor too low when hot-pressing for
successfully preparing MEA specimens. In this report, we have reported a two-step method by
which reference electrodes were completely imbedded into electric current lead-in membranes in
the first step. Because of this, we were able to use fairly reduced temperature and pressure
conditions without markedly disturbing test membranes in the following second step.
Consequently, the accuracy, reliability and reproducibility of the ion conductivity measurements
using the 4-probe method in the direction of thickness have been significantly enhanced.
3-2 Identifying cause of failure of MEA specimens from O/L error messages in
electrochemical measurement
When using the impedance gain/phase analyzer and electrochemical interface measuring
system of Solartron Instruments to measure the proton conductivity in the direction of thickness
of polymeric electrolyte membrane using the 4-probe method, RE1 O/L, RE1-RE2 O/L, and
Current O/L and Current DVM O/L errors frequently occurred on the Potentiostat/Galvanostat
electrochemical device (Model 1287, electrochemical interface). 6) These messages, combined
with the measuring principle of the electrochemical device used, may work as an informative
guide for determining the failure cause of the MEA specimen, i.e., what defects have been
observed and/or what failures have developed when measuring MEA specimens. For example,
the appropriate conditions for the manufacture and measurement of MEA specimens can be
found more effectively and rapidly based on analyses of these errors.
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Espec Technology Report No.23

Measuring Conductivity of Proton Conductive Membrane in the direction of thickness, partⅡ:
using the 4-probe method in the direction of thickness
As mentioned in the connections and equivalent circuit of MEA specimen while measuring by the
membrane thickness 4-probe method in Fig.3, the Potentiostat/Galvanostat was used to apply
AC potential perturbation to the terminals of CE and WE while simultaneously sampling the
electric potential signals between the terminals of RE1 and RE2. When error messages of RE1 O/L
and/or RE1-RE2 O/L occur, they indicate that a higher voltage drop than the 14.5 V limit of the
device has developed between the terminals of RE1 and the ground and/or the terminals of RE1
and RE2. An important phenomenon found while measuring is that the error messages RE1 O/L
and RE1-RE2 O/L occurred simultaneously during the measuring period with a frequency range
lower than 10 kHz. With the WE terminal as the ground for the instrument as shown in Fig.3, it
can only be concluded that the impedance between the terminals of RE1 and RE2 rather than that
between RE2 and WE was overloaded. This may have come from excessive interface resistance
or insufficient interface capacitance (or both) for reference electrodes RE1 and RE2, as shown in
Fig.3. Excessive interface resistance RctRE1 or RctRE2 is thought to have come from poor contact
between the test membrane and reference electrode RE1 or RE2, or disconnected electrode
wires. The following causes of failure can be expected: the snapping-off of electrode wires, the
shielding of electrode terminals by the insulated coating tube or its fragments that may come
from the stretching forward and/or the breaking up of the coating layer of the electrode wire, and
unstable contact between the reference electrode and the test membrane.
4
Observations and discussion for measuring
4-1 Effect of manufacturing conditions of MEA specimens
Effects of hot-pressing conditions and reference electrode materials on MEA measuring
performance are listed in Table 2 for measurements of proton conductivity of Nafion117 ®
membrane using the 4-probe method in the direction of thickness using the AC impedance
technique.
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Espec Technology Report No.23

Measuring Conductivity of Proton Conductive Membrane in the direction of thickness, partⅡ:
using the 4-probe method in the direction of thickness
Table 2 Effects of hot-pressing conditions and electrode material
on MEA measuring performance
Hot-pressing temperature
/ pressure
Forming method
/ electrode material
One-step
Two-step*
Teflon-Pt
Varnish-Pt
Polyester-Cu
150℃ 80℃
40 kgf cm -2 200 kgf cm -2 400 kgf cm -2 40 kgf cm -2 200 kgf cm -2 400 kgf cm -2
Stretched
coating
Unstable
performance
Poor
performance
Wire break,
Stretched
coating
- 10 -
Wire break,
Stretched
coating
Wire break Wire break
Poor
performance
Wire break
Teflon-Pt - - -
Varnish-Pt - - -
Polyester-Cu - - -
Stretched
coating
Unstable
performance
Good
performance
Stretched
coating
Good
performance
Excellent
performance
Wire break,
Stretched
coating
Wire break,
Stretched
coating
Wire break Wire break
Poor
performance
Stretched
coating
Unstable
performance
Good
performance
Poor
performance
Wire break,
Stretched
coating
Poor
performance
Unstable
performance
*:Reference electrode wires were previously imbedded into electric current lead-in membranes
by hot-pressing at 150℃ and 400 kgf cm -2 for 1 min in the first step
The one-step method in MEA manufacturing refers to a technique in which the MEA specimen is
completed using a single hot-pressing process with the laminate stack sandwiched by two electric
current lead-in membranes, two reference electrode wires, and one test membrane. Using the
one-step method, shown in Table 2, MEA specimens prepared at relatively lower temperature or
pressure afforded a comparatively higher measuring performance for all three reference
electrode materials used, more obviously in the case of Cu/polyester coated wire. On the other
hand, measuring performance of the MEA specimens was enhanced dramatically with the
two-step method, which features a preceding hot-pressing process by which the reference
electrode was imbedded into the electric current lead-in membranes. The results exhibited the
marked effectiveness of the two-step method over the one-step method. Moreover, Table 2 also
reveals an increase in the measuring performance of the MEA specimens with the use of
electrode material in the following order: Pt/Teflon, Pt/varnish, and Cu/polyester.
Microscope analysis was used to clarify the mechanism of failure of the MEA specimens,
observing and analyzing reference electrodes that underwent hot-pressing treatments. Typical
failure examples of reference electrodes are shown in Photo 1. These failures occurred after first
undergoing a hot-pressing process in the first step when using the two-step method.
Espec Technology Report No.23

Measuring Conductivity of Proton Conductive Membrane in the direction of thickness, partⅡ:
using the 4-probe method in the direction of thickness
Polyester-Cu
Hot-pressing: 150℃, 400kgf cm -2
10 min
Snapping-off of Cu wire and breaking-up of the
coating layer can be observed due to the higher
temperature and pressure, and the longer
hot-pressing time.
Polyester-Cu
Hot-pressing: 150℃, 40kgf cm-2 1 min
With lower pressure and shorter hot-pressing time,
the integrity of the reference electrode was
significantly improved. As less pressure than 40kgf
cm-2 was applied, the adherence of the electrode into
the electric current lead-in membrane degraded.
However, shortened pressing time was viable.
Varnish-Pt
Hot-pressing: 150℃, 400kgf cm -2
1 min
Identical conditions to (A) except time of
hot-pressing. However, marked cutting was induced.
The result is considered as due to poor malleability of
Pt wire compared to Cu.
Photo 1 Typical failure examples of reference electrodes occurring after the first
hot-pressing process in the two-step method
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Espec Technology Report No.23

Measuring Conductivity of Proton Conductive Membrane in the direction of thickness, partⅡ:
using the 4-probe method in the direction of thickness
Photo 1 (C) exhibits an important conclusion to be drawn: a conductor with excellent
malleability should be selected as the reference electrode, e.g., Au wire other than Pt should be
used instead of Cu wire when a strongly corrosive environment is involved.
On the other hand, we also tried using Teflon-Pt-coated wire as the reference electrode and
observed the MEA specimen. We found that besides causing the wire to snap off and breaking up
the coating layer, the Teflon coating layer became badly elongated and covered the entire
conducting tip of the electrode. This result is considered to stem from weaker adherence between
the surface of the Pt wire and the Teflon coating layer when hot-pressed at the specified
treatment temperature.
From the above observations, it has been confirmed that the stretching, breaking up and
covering of the coating layer on the reference electrode as well as the cutting of the conducting
wire have independently and/or jointly resulted in occurrences of O/L error messages in the
electrochemical device.
In summary, the following measures are very important to a better measuring performance of
the MEA specimen: adapting the two-step method, selecting the proper hot-pressing
temperature, pressure, and time while taking into account both the firmness and the integrity of
the reference electrode, and choosing the suitable conducting and coating materials for the
reference electrode based on the applied membrane environment.
4-2 Influencing of the measuring cell
As described above, it is important to manufacture an MEA specimen free of any inherent
defects. Furthermore, it is also necessary for a custom-designed measuring cell to be used to
connect the ultra-fine reference electrode terminal of approximately 100 μm in diameter with
external electrochemical devices, because connection reliability exerts a major influence on
measurability and accuracy. A special measuring cell has been designed intended for exclusive
use with the 4-probe method in the direction of thickness. This cell provides easy connecting
operation, stable and unaffected internal contact in the MEA specimen while connecting, and the
necessary external connection reliability.
- 12 -
Espec Technology Report No.23

Measuring Conductivity of Proton Conductive Membrane in the direction of thickness, partⅡ:
using the 4-probe method in the direction of thickness
4-3 Proton conductivity measurement in the direction of thickness with the Nafion117 ®
membrane
The 2- and 4-probe methods in the direction of thickness and the 4-probe method in the
in-plane direction were used to study the proton-conducting properties of the Nafion117 ®
membrane pretreated by hot-pressing at 150℃ at various pressures. Fig.4 shows typical
impedance spectra for membranes pretreated at 150℃ and 1200 kgf cm -2 . These were obtained
using the membrane thickness 4-probe method in an environment of 30℃ at 60%rh.
Near constant resistance and almost 0o of phase angle were obtained in Bode plots (A) and (B)
within the frequency range of between 0.01 Hz and 9000 Hz. Meanwhile, concentrated points with
a narrow convergence domain were displayed in the Cole-Cole plot of Fig.4(C). These results
indicate that the 4-probe method in the direction of thickness is viable in practice, exhibiting good
measurement accuracy.
Measurement environment: 30℃, 60%rh
Membrane treatment: 150℃, 1200 kgf cm -2
A and B: Bode plots, C: Cole-Cole plot
Inset shows detail of concentrated point.
Fig.4 Typical impedance spectra obtained using the 4-probe method in the direction
of thickness for Nafion117 ® membrane
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Espec Technology Report No.23

Measuring Conductivity of Proton Conductive Membrane in the direction of thickness, partⅡ:
using the 4-probe method in the direction of thickness
Fig.5 showed the measurement values for Nafion117 ® pretreated at 150℃ at various pressures
using the membrane plane 4-probe method and membrane thickness 2- and 4-probe methods.
Here, it should be noted that as a comparison standard, the measurements for these membranes
were also carried out using the conventional 4-probe method in the in-plane direction and the
2-probe method in the direction of thickness. For membranes pretreated at 150℃ and 1200 kgf
cm -2 , the proton conductivity values measured using the 2- and 4-probe methods in the direction
of thickness fit very well, verifying the effectiveness of the 4-probe method in the direction of
thickness. However, when compared to measuring in the in-plane direction using the 4-probe
method, proton conductivity values in the direction of thickness were found to have significantly
decreased. In order to make clear the actual causes, i.e., either from the immaturity of the
measurement technology developed or from the degenerated property of the membrane,
measurements were also carried out using the 4-probe methods in the in-plane and thickness
directions to measure a membrane heat-treated at 150℃ but not pressurized.
As Fig.5 shows, good conformity exists for the measurements not only between the values in the
in-plane and thickness directions for the membrane pressurized at 0 kgf cm -2 but also with those
in the in-plane direction for the membrane treated at 1200 kgf cm -2 . These results indicate that
after hot-pressing at higher temperature and pressure, proton conductivity in the direction of
thickness of the Nafion117 ® membrane was significantly degraded. Merely a simple heat
treatment with no pressurizing process did not induce the marked anisotropy in the proton
conductance of the membrane.
Measurement environment: 30℃, 30, 60, and 90%rh
Membrane treatment: 150℃, 0 and 1200 kgf cm -2
Fig.5 Proton conductivity measurements using the 4-probe method in the in-plane
direction, and the 2- and 4-probe methods in the direction of thickness for
Nafion117 ® membrane
From the above we may conclude that the 4-probe method may be employed in the direction of
thickness and this method is conducive to the complete evaluation of the ion conductance of the
electrolyte membrane with higher stability, accuracy and reproducibility.
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Espec Technology Report No.23

Measuring Conductivity of Proton Conductive Membrane in the direction of thickness, partⅡ:
using the 4-probe method in the direction of thickness
5
(1) More attention should be paid to the following items as influencing factors in the 4-probe
method in the direction of thickness: the species and characteristics of the conductor and the
coating layer materials constituting reference electrodes, the method of fabricating MEA
specimens, the temperature and pressure conditions in hot-pressing, and connections with
external devices.
(2) Anisotropic ion conductance can be induced over the directions of thickness and in-plane for
Nafion117 ® -like electrolyte membranes when pretreated at higher temperature and
pressure.
(3) The 4-probe technique may be employed in the direction of thickness in real measurements
of the ion-conducting electrolyte membrane.
6
Conclusions
Acknowledgement
The authors would like to express their gratitude to Mr. Zyun Siroma of the National Institute of
Advanced Industrial Science and Technology (AIST) for helpful instruction and useful discussions.
[Bibliography]
1) K. M. Cable et al., Chem. Mater., 7, p.1601, 1995.
2) Shuhua Ma and Zyun Siroma, Proceedings of the 46th Battery Symposium in Japan, 2G-18,
2005.
3) Shuhua Ma, Akiko Kuse, Zyun Siroma and Kazuaki Yasuda, Espec Technology Report, No. 20,
P.12-20, 2005.
4) Shuhua Ma, Zyun Siroma and Hirokazu Tanaka, J. Electrochem. Soc., Vol. 153, No. 12,
A2274-A2281, 2006.
5) C. H. Lee et al., Ind. Eng. Chem. Res., Vol. 44, p. 7617-7626, 2005.
6) Solartron Instruments, Model 1287 Electrochemical Interface, Instruction manual, issued by
TOYO corporation.
- 15 -
Espec Technology Report No.23

Introducing ESPEC EUROPE GmbH
Topic
Introducing ESPEC EUROPE GmbH
Masago Iwashima, Espec Europe GmbH
1
Introduction - A letter from Yoshinobu Matsumura, Managing Director -
Photo 1 Yoshinobu Matsumura, Managing Director, Espec Europe GmbH
Greetings,
I am Yoshinobu Matsumura, Managing Director, Espec Europe GmbH. I would like to express
my sincere appreciation for your continued patronage of Espec and our products.
First, I would like to give a brief overview of how Espec has approached our dealings in the
European market to this point. In 1988, Espec established a local corporation in Europe and
began pursuing business development in Europe and in the old Soviet Union. Despite our efforts
to expand into the Soviet market, shortly thereafter, as I’m sure you are well aware, the Soviet
Union collapsed. Being considerably affected by that collapse, our temporary withdrawal
became unavoidable. However, within the scope of our global development, the European
market holds substantial promise, and we foresee tremendous improvement in the Russian
market as well, leading to our renewed efforts to take up this challenge once more after a
15-year hiatus.
In August 2004, we stationed representatives at an office we established in Frankfurt. In 2005,
we moved our location to Munich, where our organizational framework evolved to a branch
office. While a number of significant challenges remain, we are indebted to your patronage that
has contributed to our favorable business results. In addition, from October 1, 2006, our new
line-up is available. We have also established the new Espec Europe GmbH, which is operating
in Munich. Based on the management philosophy of the Espec Group, we are striving to achieve
a “corporation of global excellence” to develop a global business that is based on a management
framework of transparency and respect for the laws and that meets the expectations of our
global customers.
As a European marketing company, our primary theme is to improve the satisfaction rate of our
valued customers. Based on the structure of our local operational framework and our global
network in each country, we are striving to make our support framework even better for each
valued customer in the EU and Russia.
We are indebted to you all for your continued patronage of Espec and our products.
Yoshinobu Matsumura, Managing Director, Espec Europe GmbH
- 16 -
Espec Technology Report No.23

Introducing ESPEC EUROPE GmbH
2
The mission of Espec Europe GmbH
2-1 With the establishment of Espec Europe GmbH comes our commitment: improving
service to our valued customers
“To promote viewing, using, and knowing the value of Espec products”
1. Closer operation : We are supplying services from a location that is closer to the
customer geographically and in time. We are actively participating in
activities such as exhibitions within the various European countries.
2. Better inventory : We will provide European inventory for products with strong demand:
Except for special order items, Espec will secure inventory for standard
products in an effort to provide much quicker delivery than has been
available.
3. More complete service : Our well-trained staff, proficient in English, German, and Japanese,
and including technical experts, are well prepared to respond promptly
and in detail to your inquiries. (We shall introduce the staff below.)
2-2 Examples of products handled by Espec Europe GmbH -Latest information-
For details, visit our web site:http://www.espec.co.jp/english/products/products.html
Thermal Shock Chamber TSD-100
Two-zone thermal shock chamber ideally suited for
MIL/IEC/JASO test standards.
This new Thermal Shock Chamber is capable of subjecting
specimens to uniform thermal stress with a 100 L test area
and outstanding thermal distribution characteristics, making
them ideally suited for use in a wide range of applications
from research and development to inspection and
production.
- Compatible with MIL-STD-883 and other test standards
- Improved temperature distribution performance
- Reduced test time by moving between two test areas
- Incorporate new Specimen Temperature Trigger (STT)
function
- Reduced power consumption
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Espec Technology Report No.23

Introducing ESPEC EUROPE GmbH
Rapid-Rate Thermal Cycle Chamber TCC-150
Electromigration Evaluation System (AEM-2000)
Advent of the Rapid-Rate Thermal Cycle Chamber just
suited for quick changes in specimen temperature, covering
various applications from JEDEC standard tests to
screening.
The Rapid-Rate Thermal Cycle Chamber incorporates new
technologies, such as a specimen temperature control that
maintains linear specimen temperature change rates,
during rapid thermal cycling, and temperature ramp control.
Espec offers a new chamber that sets the industrial standard
for the new era of thermal cycling.
- Conformity to JEDEC (JESD22-A104-B) standard test
- New temperature ramp control functions
- Specimen temperature control and air temperature control
- Uniform temperature load and highly repeatable
temperature change rate.
Increasing use is being made of microfabrication and new
materials in order to increase the levels of performance and
integration achieved with semiconductor devices. And as the
operating life of devices depends on microfabrication and
such new materials, it has become increasingly important to
evaluate electromigration under high-precision
life-acceleration conditions. High-precision control is used
for the temperature (max. 400℃) and current stress that
form the main factors in this life acceleration. A Black's
model equation and analytical software have been provided
to determine product life.
- Electromigration testing is available at 1μA, 400℃
- Capable of testing up to 240 channels per cabinet
- Newly developed highly reliable board and socket
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Espec Technology Report No.23

Introducing ESPEC EUROPE GmbH
3
Introducing the Espec GmbH staff
These are the members of the Espec GmbH staff. They will be pleased to assist you with any
inquiries.
Mitsuru Yui
Manager
Service Department
Language proficiency: Japanese, English
Christian Witte
Finance & Administration Manager
Language proficiency: German, English
(Studying Japanese)
Photo 2 Espec GmbH staff (1)
- 19 -
Frank Feiler
Area Manager
Language proficiency: German, English,
Japanese
Masago Iwashima
Marketing Assistant
Sales Department
Language proficiency: Japanese, English
(Studying German)
Espec Technology Report No.23

Introducing ESPEC EUROPE GmbH
4
Christine Spath
Sales & Marketing
Language proficiency: German, English
Introducing our new office
- 20 -
Gabriele Opl
Accounting
Language proficiency: German, English
Photo 3 Espec GmbH staff (2) -Consultants-
Coinciding with the establishment of Espec GmbH, we began operations at our new location
from October 1, 2006. We are situated in the main district of Munich quite near the central station,
with very convenient public access. We would be honored to have you come by our office any time
you are in Munich. All of our staff is sincerely looking forward to your visit.
Photo 4 Location of our new office
Espec Technology Report No.23

Introducing ESPEC EUROPE GmbH
Access
(1) By public transportation:
Get off the train at Hauptbahnhof (Central
Station) and take the Nord Seite exit (exit
escalator next to the Blumen Knauer flower
shop). Go straight ahead on Dachauer Strasse
(between Schlecker and Pension). We are
about 5 minutes from the station on foot. (Our
entrance is on the Dachauer Strasse side,
between the Plus supermarket and the King’s
Hotel.)
(2) By car:
Please use the public parking near our office.
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Fig.1 Office map
Below is our address and contact information. We shall be pleased to provide our full guidance and
support to our valued friends.
ESPEC EUROPE GmbH
Address : Dachauer Strasse 11, D-80335 München
Tel. : +49(0)89 1893 963-0 (main)
Fax. : +49(0)89-1893 963-79
URL : http://www.espec.de/
E-mail : info@espec.de
EU Sales Department, International Business Headquarters,
Espec Corporation
Tel. : +81-6-6358-4785
Fax. : +81-6-6358-4786
Espec Technology Report No.23