INTERNATIONAL SESSION ON ELECTRO-MECHANICAL DEVICES 2002 (IS-EMD 2002)

INTERNATIONAL SESSION ON ELECTRO-MECHANICAL DEVICES 2002 (IS-EMD 2002)

(Record and Abstract)
September 14-15, 2002
Keio University, Yagami Campus, Yokohama, Japan

Sponsorship:: Technical group of Electromechanical Devices in Electronics Society of the Institute of Electronics. Information and Communication Engineers.
Co-sponsored:: The Research and Engineering Meeting of Electromechanical Components and Contact Technology, IEEE CPMT Society, Tokyo Chapter, Faculty of Science & Technology, Keio University.

Technical program
Thursday, November 14, 2002

<<Session1>> - Contact Phenomena -

1. EMD2002-56 [Invited Paper]: Surface Damage in Hertzian Contact Area Caused by Repeating Normal Loading Without Any Tangential Slip; Tadashi Sasada (Prof. Emeritus, Tokyo Inst. of Technology); An experimental study was carried out to learn about the damage of contacting surfaces through repeated normal loadings without any tangential slip. To achive this purpose, two steel balls with the same size and materials were placed in contact under a cyclically oscilating normal load. Surface damages were observed only in the peripheral annulus of the Hertzian circle, where a contact-separation was repeated; while no damage occurred in the central zone of the Hertzian circle, where the normal stress and the amplitude of the varying pressure were high. The effect of environmental gases and liquids on the damage was also studied.

2. EMD2002-57: Contact Resistance law for elasto-plastic domains in the force range (1mN - 10N); X.Hernot, A.Senouci, A. El Manfalouti and N. Ben Jemaa (Univ. of Rennes I); In this paper, we try to establish a power law for contact resistance versus force R_c=K_cF_c^-n, and we determine via experimental measurements and theoretical calculations, the constants n and K_c in the force range (1mN-4N) for bulk metal (Ag,Au,Pd,Ni) used in various applications (microswitches,connectors).
The main experimental results of contact resistance are the occurrence of two decrease domains versus progressive load indentation. The first regime corresponds to the earlier touch of the coupon by the probe at force <10g. This elastic regime evolves to a plastic regime for medium force>10g. At the transition the exponent value n changes from 0.33 to 0.5 and induce K_c. value increasing. Theoretical and computational approaches applied to the elasto-plastic model, confirm the occurrence of these two regimes. Although the calculated values of n are in good agreement with experimental values, some discrepancy between measured and calculated K_cvalues take place.

3. EMD2002-58: Influence of Thermal Stress on Contact Resistance of Mounted Electrical Contacts on Printed Circuit Board; Masanari Taniguchi, Hiroyuki Ishida and Tasuku Takagi (Tohoku Bunka Gakuen Univ.); In this study, the measured results are presented on the contact resistance of mounted electrical contacts on the printed circuit board (PCB) surface due to thermal stress, along with the measurement of the deformation of PCB surface due to thermal stress by applying the Holographic Pattern Measuring System (HPMS). Some variations are shown of the contact resistance due to thermal stressed PCB deformation that was quantitatively measured by using the HPMS, which were difficult so far by the other conventional methods. In additions, we have had some relationship between the contact resistance and the micro displacement of the contact point which relates a michro-scopic displacement of contact point due to thermal deformation of PCB.

4. EMD2002-59: Bridge Voltage Waveforms in Ag and Pd Contacts Observed in Very Slowly Opening Contacts with Micro-Step Separation; Hiroyuki Ishida, Masanari Taniguchi and Tasuku Takagi (Tohoku Bunka Gakuen Univ.); Bridge-voltages were observed when the contacts were step likely separated with 0.5μm and kept stationary gaps until the next step separation came, and the durations of stationary gap were changed. The observed bridge waveforms have shown periodic variations. Here, we show some typical bridge-voltage waveforms.

5. EMD2002-60: MInfluence of Silicone Vapor on Micro-Motor Reliability; Terutaka Tamai and Kiyoshi Ogawa (Hyogo Univ. of Teacher Education); The effect of the silicone vapor on the reliability of the micro-motor was examined. Adsorbed silicone was decomposed to SiO₂ by heating due to the discharge between brush and commutator surface. It was found that the operation time until the failure was extremely shortened by the formation of SiO₂. The existence of the maximum operation time until the failure was found as depending on the number of revolution. For the higher revolution, many amounts of SiO₂ accumulated by the decomposition of the silicone shorten the operation time. For lower revolution, as the torque of the motor reduces, the operation time also shortens. Therefore, the maximum operation time exists for optimum revolution.

6. EMD2002-61: An Effect of Inert Gas on Surface Film Formation and Voltage Drop of Sliding Contacts; Takahiro Ueno, Noboru Morita (Nippon Institute of Tech.) and Koichiro Sawa (Keio Univ.); The sliding contact behavior is important for collecting current mechanism. In this study, the effect of ambient gas including inert gas on surface film formation and contact voltage drop was examined when the atmosphere is changed from low pressure to atmospheric pressure. Furthermore, the sliding surface conditions were observed by SEM, EDX and XPS analyses after the test operation. From these results, in case of the sliding contact in inert gaseous environment (Nitrogen and Argon), it is confirmed that the contact voltage drop tends to increase as if oxide film may be formed. However, it is made clear that any chemically generated surface film is hard to be formed in the inert gases environment by the chemical element analysis. As for these phenomena, we propose a model for physically absorbed surface film, and the relationship between inert gases and sliding contact phenomena is discussed.

<<Session2>> - Telecom and automotive relays -

7. EMD2002-62 [Invited Paper]: Telecom-and Signal-Relays with Gastight Plastic Sealed Housings for Enhanced Relay Performance; Werner Johler (Tyco Electronics AXICOM); Telecom- and Signal Relays with gastight plastic sealed housings enables the usage of inert and highly insulating gases. Although plastic sealed housings are used, optimized designs can keep the gas during the entire life of more than 25 years.
The application of this technology allows the application of highly insulting gases like SF₆ and result in a significant reduction of the relay size as reduced physical dimensions can be applied. With unchanged distances a significantly better dielectric performance can be achieved, without a relevant cost increase.
Furthermore the inert switching atmosphere increases the switching characteristics or reduces the consumption of precious metals for the contacts. Even the usage of less precious metals like tungsten or ruthenium might be possible for switching typical telecommunication signals.

8. EMD2002-63: Design Expert System and Visual Simulation of Miniature Electromagnetic Relay; Degui CHEN, Jingshu ZHANG, Honggang XIANG, Gang LIU and Linmin HUANG (Xi'an Jiaotong Univ.); In this paper, the application of expert system in small electromagnetic relay design is researched. The equivalence magnetic circuit model is acquired by applying software ANSYS, which analyzed the 3D magnetic field distribution of electromagnetic relay. Combining Visual C++6.0 with OpenGL technology, the model of relay can be intuitionally displayed in the software. Using the expert system can greatly shorten the design period of product, and the results satisfied the technical requirements.

9. EMD2002-64: An experimental study on operating characteristics of Ag, Pd and Cu contacts in argon atmosphere; Makoto Hasegawa, Kenta Imai (Chitose Inst. of Science & Tech.), Jiro Makimoto and Koichiro Sawa (Keio Univ.); In order to investigate influences of surrounding atmospheres on electrical contact phenomena, Ag, Pd and Cu contacts were operated in argon atmosphere up to 30,000 operations to interrupt DC inductive load currents of 1A and 3A at 20V. Arc discharge characteristics (arc duration and voltage waveforms), contact resistance characteristics, and surface damages were measured, and compared with the results obtained in air and nitrogen atmosphere. The measured results showed that arc duration in argon tends in general to be longer than that in nitrogen. Contact resistance of the argon samples sometimes showed more fluctuation than the air/nitrogen samples. Those measured results will be presented herein.

10. EMD2002-65 [Invited Paper]: Electrical Contacts for Automotive Applications: a Review; Zhuan-Ke Chen and Gerald J. Witter (Chugai USA); The three major failures of electrical contacts for automotive relay applications are: contact welding (or contact sticking), high contact resistance and severe contact erosion due to switching arcing. With the demand of high power and multiple functions of automotive vehicles, the switching current has be dramatically increased, it results in higher failing rate, in particular for contact welding. On the other hand, the miniaturization of electromechanical relays has lead to the reduction of mechanical spring force. This not only results in the earlier contact welding but also makes the relay more susceptible to the contact resistance and arc erosion failures.
This paper is a review of most recent studies on these three failure aspects. It describes the progress in the understanding of contact welding caused by short arcing and high contact resistance due to contamination of particles and films in relay manufacturing process and also it review the material transfer due to switching arcing. At the end, the brief considerations of electromechanical relays used in 42 volts have also been given.

11. EMD2002-66: Performance Investigation of Contact Material in 42VDC Automotive Relay; Osamu Sakaguchi, Kouya Takahashi and Toshiya Yamamoto (Tanaka Kikinzoku Kogyo); Each automotive manufacturer is making examination for bringing up of the nominal capacity of automotive buttery from 14 V to 42 V in order to meet the increase of the rate of fuel consumption and large electrification of the electric apparatus. It is known, however, that when the voltage of power source is made 42 V, it is very difficult to cut off the arc discharge that is generated on breaking for the single-break contact point, the basic structure of the traditional relay, And, for a method to solve the problem, a double-break contact mechanism which is able to widen the actual contact gap is proposed. We obtained basic knowledge of each material this time conducting endurance tests on widely-known Ag based contact materials under typical loads. As a result, Ag showed an outstanding durability under resistive load and inductive load. And, with inductive load, the AgZnO contact material showed an outstanding durability and arc cutoff capacity.

12. EMD2002-67: Relationships between growth of transferred pip and arc duration at electrical contacts mounted on relays; Takatsugu Nakayama, Junya Sekikawa and Takayoshi Kubono (Shizuoka Univ.); AgCdO12wt% contacts mounted on electromagnetic relays are tested in a dc 42V-8.4A resistive circuit as make-only-contacts and break-only-contacts. In this experience, arc duration has been measured each operation and shape of transferred pip on the contact have been taken photograph records in each 1000 operations. The transferred pip grew highly at make-only-contacts. And some contacts grew the plain hill form from the cathode to the anode. We expect that the transferred direction reverse at a certain arc length.

<<Session3>> - Microstructure & Precision measurement -

13. EMD2002-68 [Invited Paper]: System Perspective of Electromechanical Devices Development; Chih-Kung Lee, oWen-Jong Wu, Pei-Zen Chang and Long-Sun Huang (National Taiwan Univ.); Some electromechanical devices and systems produced using MEMS fabrication processes are detailed. Two precision measurement metrologies for inspecting electromechanical products are also described. As the trend of electromechanical device development is towards pursuing smaller and smaller sizes with robust mechanisms and powerful functions, micro-electric-mechanical system (MEMS) devices come with the tide of fashion. Three examples are discussed in detail in this paper: CMOS compatible sensors, RF/microwave components, and packaged and integrated passives devices. The design thinking of a new free-fall sensor, which is an accelerometer and possesses a surprisingly low frequency response and broad bandwidth, is mentioned. In addition, an AVID (Advanced Vibrometer/Interferometer Device) system for measuring tiny displacement and a Morphinscope system which has the advantages of a confocal microscope combined with a photon tunneling microscope, both developed by NTU's MEMS/NEMS group are discussed. The excellent sensing ability of the free-fall sensor and the accuracy resolution of the two measurement systems are proved by experimental verification.

14. EMD2002-69: Influence of shear vibration over Au-Au electric contact phenomenon; Noboru Wakatsuki and Yu Yonezawa (Ishinomaki Senshu Univ.); A LiNbO₃ piezoelectric actuator controls the Au-Au contact gap. The control accuracy of the actuator is within the sub-micron range. Contact voltage, contact current, displacement of electrodes, and driving voltage of the actuator were continuously and synchronously recorded by an A/D converter and send to a computer. The measured oscillograph data for 1500 contact operation were processed by the computer. Factors of discharge and bridge phenomena were derived at a contact operation. The contact load and the horizontal vibration of the contact were examined.

15. EMD2002-70: Sensor and Actuator Interaction for Nanometer Positioning Microactuators; Wen-Jong Wu, Chih-Kung Lee, Chun-Hui Lin and Zheng-De Chen (National Taiwan Univ.); The sensing mechanism of actuators is discussed in this paper. Some actuators like thermal and SMA wires actuators have a self-sensing mechanism which can be used to precisely control the displacement of actuators. The self-sensing mechanism of thermal wire actuators are detailed, analyzed and verified in this paper. Actuators cannot have a self-sensing mechanism like piezoelectric actuators since an external sensor is required in the control loop. A homodyne quadrature interferometer configuration with analog output capabilities was developed and verified on a closed-loop control of a stacked piezoelectric actuator to achieve a traceable nanometer scale precision actuating system.

16. EMD2002-71: Thermo-electromotive force of Cu-Cu contact for precision measurements; Isao Minowa (Tamagawa Univ.); Thermal electromotive forces of contact and lead cables of HP34420 digital volt/micro ohmmeter were test from room temperature up to 80 degrees. Thermal electromotive forces of lead cables were well small compare to the contact part because of their compensation. The lowest voltage condition was verified that just after polishing copper contact surface

17. EMD2002-72: Measurement of Acoustic Impedance of Capsuled Tissue Sample by Interference Method using Fused Quartz Rod as a Transmission Line; Masasumi Yoshizawa (Tokyo Metropolitan College of Tech.) Tadashi Moriya (Tokyo Metropolitan Univ.); An acoustic impedance measurement technique based on the open-short method is developed. This method allows the impedance of a sample placed in a capsule to be measured, using a fused quartz rod as a transmission line. The interference patterns are measured using an air backing while varying the gap between the end of the transmission line and the surface of the capsule, and the measurements are then repeated using a tungsten backing. The acoustic impedance of salt water calculated by this method was within an error margin of 10%.

Friday, November 15, 2002
<<Session4>> - Discharges & Related phenomena -

18. EMD2002-73 [Invited Paper]: Effect of magnetic field of arc chamber and operating mechanism on current limiting characteristics of low-voltage circuit breakers; Haitao Sun, Degui Chen, Qingjiang Liu and Jingshu Zhang (Xi'an Jiaotong Univ.); The interrupting characteristics of low voltage current limiting circuit breakers have directly relationship with the magnitude and distribution of magnetic field produced by contact system and splitter plates. In order to analyze the influence of configuration of contact system on current limiting characteristics, 3D magnetic field of arc chamber (includes contact system, arc, splitter plates) is calculated. Furthermore, the electromagnetic repulsion force of movable contact is also calculated. The results can be used to improve configuration of arc quenching chamber. The cooperation between operating mechanism and electromagnetic repulsion force are also analyzed in this paper.

19. EMD2002-74: Mass Change and Surface Morphology of Contact in Electromagnetic Contactor; Masaki Takashima, Nahoko Yamamura (Keio Univ.), Makoto Hasegawa (Chitose Inst. of Science & Tech.) and Koichiro Sawa (Keio Univ.); Electrical contacts are extensively used for telecommunication and electric power as a device directly making and breaking electrical circuit. In future those are more indispensable presence. The aim of this work is to compare between mass change and surface morphology by using two types of contact with different form. Concerning contact form, one has a curved surface electrode that is generally used; the other is notched in the center of the electrode. This contact form is made in the motif of twin contacts that give high contact reliability. Therefore we expect to attain high contact reliability with this contact form. First, we focus attention on mass change of contacts because the process of contact erosion and material transfer is less well understood. And we investigate the relation between mass change of contacts and surface morphology, arc duration, arc energy, contact resistance.
As a result, although the contact resistances of both types keep low and stable, the mass loss of notched contact is larger than generally used contact. Therefore the advantage of notched contact is not confirmed. But we confirm that mass change has close relation to surface morphology, arc duration and arc energy.

20. EMD2002-75: Relationship between gaseous phase transition and bridge phenomena in Ag, Pd break arc; Kiyoshi Yoshida, Yoshiyuki Suganami and Atsuo Takahashi (Nippon Institute. of Technology); For Ag and Pd contacts, the relation between transition boundary to gaseous phase and bridge voltage for break arc, is investigated under the several circuit condition. In both contacts, contact resistance Rc becomes maximum value at the transition boundary closed contact current Io(50). At larger current than Io(50), Rc decreases with increase of Io. In Ag contacts, the occurrence times of re-bridge rapidly decreases when transition to gaseous phase was made. Furthermore, the boiling voltage Vb of first bridge rapidly decreases at larger current than Io(50). On the other hand, in Pd contacts, the boiling voltage Vb and Vbe for first brige and last re-bridge have nearly constant value (1.2 to 1.3V) which is peculiar to the material, even if arc transits to the gaseous phase.

21. EMD2002-76: Arc Extinction at a Fixed Short Gap between Silver Electrodes; Keiichi Suhara (Tokyo National College of Technology); Arc duration was measured in constant arc gap and constant arc current conditions at silver electrodes. The duration distributes exponentially. The time constant τ and the extinction rate λ of the distribution were calculated, and related to the arc current. It was assured by silver electrode arc that, even below the so-called minimum arc current, arc ignition may occur but, in this case, the arc duration is momentary, and, as the arc current decreases, the arc extinction rate becomes large.

22. EMD2002-77: Experimental Equation of V-I Characteristics of Breaking Arc in the Air; Junya Sekikawa and Takayoshi Kubono (Shizuoka Univ.); An experimental equation of V-I characteristics of breaking arc was investigated in the air at atmospheric pressure. Material of the contact pair is Ag, Au, Cu and Ni. The time evolutions of arc voltage, arc current and gap length were measured, simultaneously. V-I characteristics were obtained from those measured values. The dependence of the arc voltage on the gap length was represented by an approximate formula as a straight line in order to obtain the experimental equation. And the dependence of the strength of electric field of arc column on the supply voltage is approximated to a straight line. Using these approximate formulae, the experimental equation of the dependence of the arc voltage on the arc current was obtained with the gap length as a parameter. It was shown that the experimental equation agreed with experimental data in the experimental conditions for each contact material.

23. EMD2002-78: 3D Dynamic MHD Arc Mathematical Model of Low Voltage Circuit Breakers; Haitao SUN; In order to reveal the complex physical phenomena in the interrupting process of low voltage circuit breakers, a 3D dynamic MHD arc mathematic model is set up in this paper according to one simple arc chamber, which model emphasizing the interaction among airflow field, arc and electrical magnetic field, and taking account of the effects of joule heat, conduction, convection, radiation and lorentz force on airflow field in arc chamber. Using this mathematical arc model, complex burning process of 3D arc in arc chamber is simulated and a new approach will be created for optimization design of arc chamber in low voltage circuit breakers. Combining with simulation of arc phenomena, a corresponding arc chamber sample is made to testify the arc mathematical model.

<<Session5>> - Connector & Related phenomena -

24. EMD2002-79 [Invited Paper]: Analysis of connector contact failure; J.G.Zhang, J.C.Gao and X.Y.Lin (Beijing Univ. of Post & Telecommunications); Large number of electronic connectors are widely used in various telecommunication systems. No matter whether it is optical telecommunications or mobile phone systems, connectors are important links for electronics. Unfortunately connector contacts are exposed in air. In China, dust and corrosion products are the main pollution in air to cause contact failure which seriously deteriorate the reliability of telecommunication systems. This paper summarizes the recent achievements obtained by our Lab on the effect of dust and corrosion products on connector contact failure. Continuous studies will be very useful to improve the contact reliability of connectors, setting up new testing methods and standards, building up experimental and computer simulation systems.

25. EMD2002-80 [Invited Paper]: Dynamic influence on contact failure; Liang-Jun Xu and Cui-Feng Feng (Beijing Univ. of Post & Telecommunications); Nowadays electronic devices and systems are widely used in various dynamic environments. It causes a kind of electrical contact instability which is easily to be ignored. That is dynamic influence on contact failure. In this paper, the investigation of contact failure connected with dynamic influences has been done, the way of analyzing the contact failure caused by dynamic factors was discussed, and the result shows that this influence could not be well covered in the experimental testing on new product.

26. EMD2002-81: Fretting in Connector Terminals Using Conducting Polymer Contacts; Jonathan Swingler and john W. McBride (Univ. of Southampton); Novel contact connector materials such as extrinsic conducting polymers improve contact performance and enables device miniaturisation. This paper presents an investigation of conducting polymer materials to minimise the effect of fretting at the contact interface of connector terminals. Initial experimental studies are presented and a mechanical model is used to describe the polymer interface slip and stick characteristics. For fretting to be minimised the polymer must be sufficiently elastic, with a high coefficient of friction with the contacting terminal, and a sufficient normal force to ensure no slip. Electrical experimental studies of a polymer-tin interface have also been carried out to characterise contact resistance performance under fretting conditions. A resistance model of the polymer interface is developed.

27. EMD2002-82: Calculations of the Influences of Geometry and Wire Gauges on the Current Carrying Capacity of IDC Links.; Achim Brenner; Horst F. Nowacki (HARTING KGaA); In this presentation mathematical calculations and FEM simulations examined the influence of the geometric design parameters on the mechanical and electrical behaviour of Insulation Displacement connections (IDC) for single wire terminations.
The mechanical calculations are used as the basis to determine the contact forces and the spring deflections of the IDC termination beam elements applied to connect different solid copper wire gauges.
In particular the influence of the contact pressure on the deformation of the solid copper wires is calculated with various diameters.
With the help of model calculations and comparative measurements of the electrical contact bulk resistances and the constriction resistances the current carrying capacity for ID- connections with different solid wire diameters can be determined.

28. EMD2002-83 [Invited Paper]: Technical Trends in Optical Fiber Connectors for Telecommunication Systems; Ryo Nagase (NTT Photonics Laboratories); Various optical fiber connectors have been developed during the 20 years since optical fiber communications systems were first put into practical use. As the domain of optical fiber communication systems expanded from trunk lines to subscriber lines and customer premises the main focus changed from performance improvement (reduction of insertion loss and reflection) to miniaturization, cost reduction and functional improvement. This paper describes the circumstances of optical connector development, the technical background, and recent trends in standard optical connectors.

29. EMD2002-84: Advanced Structure of MU-type Fixed Optical Attenuator for High Density Optical Packaging; Shuichi Yanagi and Ryo Nagase (NTT Photonics Laboratories); We newly developed an MU-type fixed optical attenuator for 4.5 mm pitch packaging. We succeeded in miniaturizing the attenuator by adopting a design employing an MUJ plug. Our fixed optical attenuator achieved a tensile strength of greater than 7 kgf, which is the same as that of a conventional fixed optical attenuator, and also exhibited good environmental and mechanical durability. Our fixed optical attenuator can be used in existing communication devices in which 4.5 mm pitch MU adaptors are already installed.

30. EMD2002-85: Estimation for Wideband Electromagnetic Field Distribution from PCB with Switching Transistor; Takashi Kasuga and Hiroshi Inoue (Akita Univ.); To analyze the electromagnetic noise radiated from PCB driven by switching device, FDTD simulation method implemented the switching transistor is developed. The electric and magnetic field distribution on the signal line driven by switching transistor is measured and/or calculated. These results show good agreement. The electric and magnetic field noise at typical impedance conditions modeled for the switching condition, i.e. ON or OFF state of transistor, are estimated by calculation. The variation for the radiation noise when the switching transistor is turned ON or OFF is large at 216MHz, whose input impedance of the signal line is small. It is speculated that the noise radiation at 10Ω signal source impedance condition that is modeled for ON condition shows good agreement with the noise distributions at the driving condition.

31. EMD2002-86: A Study on Suppression of Common-Mode Current due to a Trace on a PCB; Yoshiki Kayano, Motoshi Tanaka, Hiroshi Inoue (Akita Univ.)and Jim L. Drewniak (Univ. of Missouri at Rolla); Suppression of common-mode (CM) current on a feed cable due to a trace on a printed circuit board (PCB) is studied experimentally and with finite-difference time-domain (FDTD) modeling. Six kinds of different structure of PCBs were employed for the investigation of CM current. Results show that shielded structure is effective in suppressing the CM current which might be the source of CM radiation, as well as direct radiation from the trace. The terminating resistor is no effect on the suppression of CM current at all of the PCB structure. This study can be the basic consideration to realize a PCB structure which is effective on the suppression of the CM current.

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